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![Mel Gorman](/assets/img/avatar_default.png)
__GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1147 lines
28 KiB
C
1147 lines
28 KiB
C
/*
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* 2002-10-18 written by Jim Houston jim.houston@ccur.com
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* Copyright (C) 2002 by Concurrent Computer Corporation
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* Distributed under the GNU GPL license version 2.
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*
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* Modified by George Anzinger to reuse immediately and to use
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* find bit instructions. Also removed _irq on spinlocks.
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*
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* Modified by Nadia Derbey to make it RCU safe.
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*
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* Small id to pointer translation service.
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*
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* It uses a radix tree like structure as a sparse array indexed
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* by the id to obtain the pointer. The bitmap makes allocating
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* a new id quick.
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*
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* You call it to allocate an id (an int) an associate with that id a
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* pointer or what ever, we treat it as a (void *). You can pass this
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* id to a user for him to pass back at a later time. You then pass
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* that id to this code and it returns your pointer.
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*/
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#ifndef TEST // to test in user space...
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/export.h>
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#endif
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#include <linux/err.h>
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#include <linux/string.h>
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#include <linux/idr.h>
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#include <linux/spinlock.h>
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#include <linux/percpu.h>
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#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
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#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
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/* Leave the possibility of an incomplete final layer */
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#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
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/* Number of id_layer structs to leave in free list */
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#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
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static struct kmem_cache *idr_layer_cache;
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static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head);
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static DEFINE_PER_CPU(int, idr_preload_cnt);
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static DEFINE_SPINLOCK(simple_ida_lock);
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/* the maximum ID which can be allocated given idr->layers */
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static int idr_max(int layers)
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{
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int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
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return (1 << bits) - 1;
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}
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/*
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* Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
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* all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
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* so on.
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*/
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static int idr_layer_prefix_mask(int layer)
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{
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return ~idr_max(layer + 1);
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}
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static struct idr_layer *get_from_free_list(struct idr *idp)
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{
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struct idr_layer *p;
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unsigned long flags;
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spin_lock_irqsave(&idp->lock, flags);
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if ((p = idp->id_free)) {
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idp->id_free = p->ary[0];
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idp->id_free_cnt--;
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p->ary[0] = NULL;
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}
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spin_unlock_irqrestore(&idp->lock, flags);
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return(p);
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}
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/**
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* idr_layer_alloc - allocate a new idr_layer
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* @gfp_mask: allocation mask
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* @layer_idr: optional idr to allocate from
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*
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* If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
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* one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
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* an idr_layer from @idr->id_free.
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*
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* @layer_idr is to maintain backward compatibility with the old alloc
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* interface - idr_pre_get() and idr_get_new*() - and will be removed
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* together with per-pool preload buffer.
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*/
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static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr)
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{
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struct idr_layer *new;
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/* this is the old path, bypass to get_from_free_list() */
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if (layer_idr)
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return get_from_free_list(layer_idr);
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/*
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* Try to allocate directly from kmem_cache. We want to try this
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* before preload buffer; otherwise, non-preloading idr_alloc()
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* users will end up taking advantage of preloading ones. As the
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* following is allowed to fail for preloaded cases, suppress
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* warning this time.
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*/
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new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN);
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if (new)
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return new;
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/*
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* Try to fetch one from the per-cpu preload buffer if in process
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* context. See idr_preload() for details.
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*/
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if (!in_interrupt()) {
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preempt_disable();
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new = __this_cpu_read(idr_preload_head);
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if (new) {
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__this_cpu_write(idr_preload_head, new->ary[0]);
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__this_cpu_dec(idr_preload_cnt);
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new->ary[0] = NULL;
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}
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preempt_enable();
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if (new)
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return new;
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}
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/*
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* Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
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* that memory allocation failure warning is printed as intended.
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*/
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return kmem_cache_zalloc(idr_layer_cache, gfp_mask);
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}
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static void idr_layer_rcu_free(struct rcu_head *head)
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{
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struct idr_layer *layer;
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layer = container_of(head, struct idr_layer, rcu_head);
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kmem_cache_free(idr_layer_cache, layer);
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}
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static inline void free_layer(struct idr *idr, struct idr_layer *p)
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{
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if (idr->hint == p)
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RCU_INIT_POINTER(idr->hint, NULL);
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call_rcu(&p->rcu_head, idr_layer_rcu_free);
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}
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/* only called when idp->lock is held */
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static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
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{
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p->ary[0] = idp->id_free;
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idp->id_free = p;
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idp->id_free_cnt++;
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}
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static void move_to_free_list(struct idr *idp, struct idr_layer *p)
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{
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unsigned long flags;
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/*
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* Depends on the return element being zeroed.
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*/
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spin_lock_irqsave(&idp->lock, flags);
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__move_to_free_list(idp, p);
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spin_unlock_irqrestore(&idp->lock, flags);
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}
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static void idr_mark_full(struct idr_layer **pa, int id)
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{
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struct idr_layer *p = pa[0];
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int l = 0;
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__set_bit(id & IDR_MASK, p->bitmap);
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/*
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* If this layer is full mark the bit in the layer above to
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* show that this part of the radix tree is full. This may
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* complete the layer above and require walking up the radix
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* tree.
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*/
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while (bitmap_full(p->bitmap, IDR_SIZE)) {
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if (!(p = pa[++l]))
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break;
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id = id >> IDR_BITS;
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__set_bit((id & IDR_MASK), p->bitmap);
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}
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}
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static int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
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{
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while (idp->id_free_cnt < MAX_IDR_FREE) {
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struct idr_layer *new;
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new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
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if (new == NULL)
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return (0);
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move_to_free_list(idp, new);
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}
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return 1;
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}
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/**
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* sub_alloc - try to allocate an id without growing the tree depth
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* @idp: idr handle
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* @starting_id: id to start search at
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* @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
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* @gfp_mask: allocation mask for idr_layer_alloc()
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* @layer_idr: optional idr passed to idr_layer_alloc()
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*
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* Allocate an id in range [@starting_id, INT_MAX] from @idp without
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* growing its depth. Returns
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*
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* the allocated id >= 0 if successful,
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* -EAGAIN if the tree needs to grow for allocation to succeed,
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* -ENOSPC if the id space is exhausted,
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* -ENOMEM if more idr_layers need to be allocated.
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*/
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static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
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gfp_t gfp_mask, struct idr *layer_idr)
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{
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int n, m, sh;
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struct idr_layer *p, *new;
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int l, id, oid;
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id = *starting_id;
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restart:
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p = idp->top;
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l = idp->layers;
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pa[l--] = NULL;
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while (1) {
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/*
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* We run around this while until we reach the leaf node...
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*/
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n = (id >> (IDR_BITS*l)) & IDR_MASK;
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m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
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if (m == IDR_SIZE) {
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/* no space available go back to previous layer. */
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l++;
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oid = id;
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id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
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/* if already at the top layer, we need to grow */
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if (id > idr_max(idp->layers)) {
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*starting_id = id;
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return -EAGAIN;
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}
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p = pa[l];
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BUG_ON(!p);
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/* If we need to go up one layer, continue the
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* loop; otherwise, restart from the top.
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*/
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sh = IDR_BITS * (l + 1);
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if (oid >> sh == id >> sh)
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continue;
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else
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goto restart;
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}
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if (m != n) {
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sh = IDR_BITS*l;
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id = ((id >> sh) ^ n ^ m) << sh;
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}
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if ((id >= MAX_IDR_BIT) || (id < 0))
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return -ENOSPC;
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if (l == 0)
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break;
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/*
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* Create the layer below if it is missing.
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*/
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if (!p->ary[m]) {
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new = idr_layer_alloc(gfp_mask, layer_idr);
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if (!new)
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return -ENOMEM;
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new->layer = l-1;
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new->prefix = id & idr_layer_prefix_mask(new->layer);
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rcu_assign_pointer(p->ary[m], new);
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p->count++;
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}
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pa[l--] = p;
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p = p->ary[m];
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}
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pa[l] = p;
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return id;
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}
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static int idr_get_empty_slot(struct idr *idp, int starting_id,
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struct idr_layer **pa, gfp_t gfp_mask,
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struct idr *layer_idr)
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{
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struct idr_layer *p, *new;
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int layers, v, id;
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unsigned long flags;
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id = starting_id;
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build_up:
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p = idp->top;
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layers = idp->layers;
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if (unlikely(!p)) {
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if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
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return -ENOMEM;
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p->layer = 0;
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layers = 1;
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}
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/*
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* Add a new layer to the top of the tree if the requested
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* id is larger than the currently allocated space.
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*/
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while (id > idr_max(layers)) {
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layers++;
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if (!p->count) {
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/* special case: if the tree is currently empty,
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* then we grow the tree by moving the top node
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* upwards.
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*/
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p->layer++;
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WARN_ON_ONCE(p->prefix);
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continue;
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}
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if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
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/*
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* The allocation failed. If we built part of
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* the structure tear it down.
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*/
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spin_lock_irqsave(&idp->lock, flags);
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for (new = p; p && p != idp->top; new = p) {
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p = p->ary[0];
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new->ary[0] = NULL;
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new->count = 0;
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bitmap_clear(new->bitmap, 0, IDR_SIZE);
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__move_to_free_list(idp, new);
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}
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spin_unlock_irqrestore(&idp->lock, flags);
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return -ENOMEM;
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}
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new->ary[0] = p;
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new->count = 1;
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new->layer = layers-1;
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new->prefix = id & idr_layer_prefix_mask(new->layer);
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if (bitmap_full(p->bitmap, IDR_SIZE))
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__set_bit(0, new->bitmap);
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p = new;
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}
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rcu_assign_pointer(idp->top, p);
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idp->layers = layers;
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v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
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if (v == -EAGAIN)
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goto build_up;
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return(v);
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}
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/*
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* @id and @pa are from a successful allocation from idr_get_empty_slot().
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* Install the user pointer @ptr and mark the slot full.
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*/
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static void idr_fill_slot(struct idr *idr, void *ptr, int id,
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struct idr_layer **pa)
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{
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/* update hint used for lookup, cleared from free_layer() */
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rcu_assign_pointer(idr->hint, pa[0]);
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rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
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pa[0]->count++;
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idr_mark_full(pa, id);
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}
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/**
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* idr_preload - preload for idr_alloc()
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* @gfp_mask: allocation mask to use for preloading
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*
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* Preload per-cpu layer buffer for idr_alloc(). Can only be used from
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* process context and each idr_preload() invocation should be matched with
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* idr_preload_end(). Note that preemption is disabled while preloaded.
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*
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* The first idr_alloc() in the preloaded section can be treated as if it
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* were invoked with @gfp_mask used for preloading. This allows using more
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* permissive allocation masks for idrs protected by spinlocks.
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*
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* For example, if idr_alloc() below fails, the failure can be treated as
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* if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
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*
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* idr_preload(GFP_KERNEL);
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* spin_lock(lock);
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*
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* id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
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*
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* spin_unlock(lock);
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* idr_preload_end();
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* if (id < 0)
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* error;
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*/
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void idr_preload(gfp_t gfp_mask)
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{
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/*
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* Consuming preload buffer from non-process context breaks preload
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* allocation guarantee. Disallow usage from those contexts.
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*/
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WARN_ON_ONCE(in_interrupt());
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might_sleep_if(gfpflags_allow_blocking(gfp_mask));
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preempt_disable();
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/*
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* idr_alloc() is likely to succeed w/o full idr_layer buffer and
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* return value from idr_alloc() needs to be checked for failure
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* anyway. Silently give up if allocation fails. The caller can
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* treat failures from idr_alloc() as if idr_alloc() were called
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* with @gfp_mask which should be enough.
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*/
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while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
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struct idr_layer *new;
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preempt_enable();
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new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
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preempt_disable();
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if (!new)
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break;
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/* link the new one to per-cpu preload list */
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new->ary[0] = __this_cpu_read(idr_preload_head);
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__this_cpu_write(idr_preload_head, new);
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__this_cpu_inc(idr_preload_cnt);
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}
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}
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EXPORT_SYMBOL(idr_preload);
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|
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/**
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* idr_alloc - allocate new idr entry
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* @idr: the (initialized) idr
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* @ptr: pointer to be associated with the new id
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* @start: the minimum id (inclusive)
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* @end: the maximum id (exclusive, <= 0 for max)
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* @gfp_mask: memory allocation flags
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*
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* Allocate an id in [start, end) and associate it with @ptr. If no ID is
|
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* available in the specified range, returns -ENOSPC. On memory allocation
|
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* failure, returns -ENOMEM.
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*
|
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* Note that @end is treated as max when <= 0. This is to always allow
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* using @start + N as @end as long as N is inside integer range.
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*
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* The user is responsible for exclusively synchronizing all operations
|
|
* which may modify @idr. However, read-only accesses such as idr_find()
|
|
* or iteration can be performed under RCU read lock provided the user
|
|
* destroys @ptr in RCU-safe way after removal from idr.
|
|
*/
|
|
int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
|
|
{
|
|
int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
|
|
struct idr_layer *pa[MAX_IDR_LEVEL + 1];
|
|
int id;
|
|
|
|
might_sleep_if(gfpflags_allow_blocking(gfp_mask));
|
|
|
|
/* sanity checks */
|
|
if (WARN_ON_ONCE(start < 0))
|
|
return -EINVAL;
|
|
if (unlikely(max < start))
|
|
return -ENOSPC;
|
|
|
|
/* allocate id */
|
|
id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
|
|
if (unlikely(id < 0))
|
|
return id;
|
|
if (unlikely(id > max))
|
|
return -ENOSPC;
|
|
|
|
idr_fill_slot(idr, ptr, id, pa);
|
|
return id;
|
|
}
|
|
EXPORT_SYMBOL_GPL(idr_alloc);
|
|
|
|
/**
|
|
* idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
|
|
* @idr: the (initialized) idr
|
|
* @ptr: pointer to be associated with the new id
|
|
* @start: the minimum id (inclusive)
|
|
* @end: the maximum id (exclusive, <= 0 for max)
|
|
* @gfp_mask: memory allocation flags
|
|
*
|
|
* Essentially the same as idr_alloc, but prefers to allocate progressively
|
|
* higher ids if it can. If the "cur" counter wraps, then it will start again
|
|
* at the "start" end of the range and allocate one that has already been used.
|
|
*/
|
|
int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
|
|
gfp_t gfp_mask)
|
|
{
|
|
int id;
|
|
|
|
id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
|
|
if (id == -ENOSPC)
|
|
id = idr_alloc(idr, ptr, start, end, gfp_mask);
|
|
|
|
if (likely(id >= 0))
|
|
idr->cur = id + 1;
|
|
return id;
|
|
}
|
|
EXPORT_SYMBOL(idr_alloc_cyclic);
|
|
|
|
static void idr_remove_warning(int id)
|
|
{
|
|
WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);
|
|
}
|
|
|
|
static void sub_remove(struct idr *idp, int shift, int id)
|
|
{
|
|
struct idr_layer *p = idp->top;
|
|
struct idr_layer **pa[MAX_IDR_LEVEL + 1];
|
|
struct idr_layer ***paa = &pa[0];
|
|
struct idr_layer *to_free;
|
|
int n;
|
|
|
|
*paa = NULL;
|
|
*++paa = &idp->top;
|
|
|
|
while ((shift > 0) && p) {
|
|
n = (id >> shift) & IDR_MASK;
|
|
__clear_bit(n, p->bitmap);
|
|
*++paa = &p->ary[n];
|
|
p = p->ary[n];
|
|
shift -= IDR_BITS;
|
|
}
|
|
n = id & IDR_MASK;
|
|
if (likely(p != NULL && test_bit(n, p->bitmap))) {
|
|
__clear_bit(n, p->bitmap);
|
|
RCU_INIT_POINTER(p->ary[n], NULL);
|
|
to_free = NULL;
|
|
while(*paa && ! --((**paa)->count)){
|
|
if (to_free)
|
|
free_layer(idp, to_free);
|
|
to_free = **paa;
|
|
**paa-- = NULL;
|
|
}
|
|
if (!*paa)
|
|
idp->layers = 0;
|
|
if (to_free)
|
|
free_layer(idp, to_free);
|
|
} else
|
|
idr_remove_warning(id);
|
|
}
|
|
|
|
/**
|
|
* idr_remove - remove the given id and free its slot
|
|
* @idp: idr handle
|
|
* @id: unique key
|
|
*/
|
|
void idr_remove(struct idr *idp, int id)
|
|
{
|
|
struct idr_layer *p;
|
|
struct idr_layer *to_free;
|
|
|
|
if (id < 0)
|
|
return;
|
|
|
|
if (id > idr_max(idp->layers)) {
|
|
idr_remove_warning(id);
|
|
return;
|
|
}
|
|
|
|
sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
|
|
if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
|
|
idp->top->ary[0]) {
|
|
/*
|
|
* Single child at leftmost slot: we can shrink the tree.
|
|
* This level is not needed anymore since when layers are
|
|
* inserted, they are inserted at the top of the existing
|
|
* tree.
|
|
*/
|
|
to_free = idp->top;
|
|
p = idp->top->ary[0];
|
|
rcu_assign_pointer(idp->top, p);
|
|
--idp->layers;
|
|
to_free->count = 0;
|
|
bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
|
|
free_layer(idp, to_free);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(idr_remove);
|
|
|
|
static void __idr_remove_all(struct idr *idp)
|
|
{
|
|
int n, id, max;
|
|
int bt_mask;
|
|
struct idr_layer *p;
|
|
struct idr_layer *pa[MAX_IDR_LEVEL + 1];
|
|
struct idr_layer **paa = &pa[0];
|
|
|
|
n = idp->layers * IDR_BITS;
|
|
*paa = idp->top;
|
|
RCU_INIT_POINTER(idp->top, NULL);
|
|
max = idr_max(idp->layers);
|
|
|
|
id = 0;
|
|
while (id >= 0 && id <= max) {
|
|
p = *paa;
|
|
while (n > IDR_BITS && p) {
|
|
n -= IDR_BITS;
|
|
p = p->ary[(id >> n) & IDR_MASK];
|
|
*++paa = p;
|
|
}
|
|
|
|
bt_mask = id;
|
|
id += 1 << n;
|
|
/* Get the highest bit that the above add changed from 0->1. */
|
|
while (n < fls(id ^ bt_mask)) {
|
|
if (*paa)
|
|
free_layer(idp, *paa);
|
|
n += IDR_BITS;
|
|
--paa;
|
|
}
|
|
}
|
|
idp->layers = 0;
|
|
}
|
|
|
|
/**
|
|
* idr_destroy - release all cached layers within an idr tree
|
|
* @idp: idr handle
|
|
*
|
|
* Free all id mappings and all idp_layers. After this function, @idp is
|
|
* completely unused and can be freed / recycled. The caller is
|
|
* responsible for ensuring that no one else accesses @idp during or after
|
|
* idr_destroy().
|
|
*
|
|
* A typical clean-up sequence for objects stored in an idr tree will use
|
|
* idr_for_each() to free all objects, if necessary, then idr_destroy() to
|
|
* free up the id mappings and cached idr_layers.
|
|
*/
|
|
void idr_destroy(struct idr *idp)
|
|
{
|
|
__idr_remove_all(idp);
|
|
|
|
while (idp->id_free_cnt) {
|
|
struct idr_layer *p = get_from_free_list(idp);
|
|
kmem_cache_free(idr_layer_cache, p);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(idr_destroy);
|
|
|
|
void *idr_find_slowpath(struct idr *idp, int id)
|
|
{
|
|
int n;
|
|
struct idr_layer *p;
|
|
|
|
if (id < 0)
|
|
return NULL;
|
|
|
|
p = rcu_dereference_raw(idp->top);
|
|
if (!p)
|
|
return NULL;
|
|
n = (p->layer+1) * IDR_BITS;
|
|
|
|
if (id > idr_max(p->layer + 1))
|
|
return NULL;
|
|
BUG_ON(n == 0);
|
|
|
|
while (n > 0 && p) {
|
|
n -= IDR_BITS;
|
|
BUG_ON(n != p->layer*IDR_BITS);
|
|
p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
|
|
}
|
|
return((void *)p);
|
|
}
|
|
EXPORT_SYMBOL(idr_find_slowpath);
|
|
|
|
/**
|
|
* idr_for_each - iterate through all stored pointers
|
|
* @idp: idr handle
|
|
* @fn: function to be called for each pointer
|
|
* @data: data passed back to callback function
|
|
*
|
|
* Iterate over the pointers registered with the given idr. The
|
|
* callback function will be called for each pointer currently
|
|
* registered, passing the id, the pointer and the data pointer passed
|
|
* to this function. It is not safe to modify the idr tree while in
|
|
* the callback, so functions such as idr_get_new and idr_remove are
|
|
* not allowed.
|
|
*
|
|
* We check the return of @fn each time. If it returns anything other
|
|
* than %0, we break out and return that value.
|
|
*
|
|
* The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
|
|
*/
|
|
int idr_for_each(struct idr *idp,
|
|
int (*fn)(int id, void *p, void *data), void *data)
|
|
{
|
|
int n, id, max, error = 0;
|
|
struct idr_layer *p;
|
|
struct idr_layer *pa[MAX_IDR_LEVEL + 1];
|
|
struct idr_layer **paa = &pa[0];
|
|
|
|
n = idp->layers * IDR_BITS;
|
|
*paa = rcu_dereference_raw(idp->top);
|
|
max = idr_max(idp->layers);
|
|
|
|
id = 0;
|
|
while (id >= 0 && id <= max) {
|
|
p = *paa;
|
|
while (n > 0 && p) {
|
|
n -= IDR_BITS;
|
|
p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
|
|
*++paa = p;
|
|
}
|
|
|
|
if (p) {
|
|
error = fn(id, (void *)p, data);
|
|
if (error)
|
|
break;
|
|
}
|
|
|
|
id += 1 << n;
|
|
while (n < fls(id)) {
|
|
n += IDR_BITS;
|
|
--paa;
|
|
}
|
|
}
|
|
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(idr_for_each);
|
|
|
|
/**
|
|
* idr_get_next - lookup next object of id to given id.
|
|
* @idp: idr handle
|
|
* @nextidp: pointer to lookup key
|
|
*
|
|
* Returns pointer to registered object with id, which is next number to
|
|
* given id. After being looked up, *@nextidp will be updated for the next
|
|
* iteration.
|
|
*
|
|
* This function can be called under rcu_read_lock(), given that the leaf
|
|
* pointers lifetimes are correctly managed.
|
|
*/
|
|
void *idr_get_next(struct idr *idp, int *nextidp)
|
|
{
|
|
struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
|
|
struct idr_layer **paa = &pa[0];
|
|
int id = *nextidp;
|
|
int n, max;
|
|
|
|
/* find first ent */
|
|
p = *paa = rcu_dereference_raw(idp->top);
|
|
if (!p)
|
|
return NULL;
|
|
n = (p->layer + 1) * IDR_BITS;
|
|
max = idr_max(p->layer + 1);
|
|
|
|
while (id >= 0 && id <= max) {
|
|
p = *paa;
|
|
while (n > 0 && p) {
|
|
n -= IDR_BITS;
|
|
p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
|
|
*++paa = p;
|
|
}
|
|
|
|
if (p) {
|
|
*nextidp = id;
|
|
return p;
|
|
}
|
|
|
|
/*
|
|
* Proceed to the next layer at the current level. Unlike
|
|
* idr_for_each(), @id isn't guaranteed to be aligned to
|
|
* layer boundary at this point and adding 1 << n may
|
|
* incorrectly skip IDs. Make sure we jump to the
|
|
* beginning of the next layer using round_up().
|
|
*/
|
|
id = round_up(id + 1, 1 << n);
|
|
while (n < fls(id)) {
|
|
n += IDR_BITS;
|
|
--paa;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(idr_get_next);
|
|
|
|
|
|
/**
|
|
* idr_replace - replace pointer for given id
|
|
* @idp: idr handle
|
|
* @ptr: pointer you want associated with the id
|
|
* @id: lookup key
|
|
*
|
|
* Replace the pointer registered with an id and return the old value.
|
|
* A %-ENOENT return indicates that @id was not found.
|
|
* A %-EINVAL return indicates that @id was not within valid constraints.
|
|
*
|
|
* The caller must serialize with writers.
|
|
*/
|
|
void *idr_replace(struct idr *idp, void *ptr, int id)
|
|
{
|
|
int n;
|
|
struct idr_layer *p, *old_p;
|
|
|
|
if (id < 0)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
p = idp->top;
|
|
if (!p)
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
if (id > idr_max(p->layer + 1))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
n = p->layer * IDR_BITS;
|
|
while ((n > 0) && p) {
|
|
p = p->ary[(id >> n) & IDR_MASK];
|
|
n -= IDR_BITS;
|
|
}
|
|
|
|
n = id & IDR_MASK;
|
|
if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
old_p = p->ary[n];
|
|
rcu_assign_pointer(p->ary[n], ptr);
|
|
|
|
return old_p;
|
|
}
|
|
EXPORT_SYMBOL(idr_replace);
|
|
|
|
void __init idr_init_cache(void)
|
|
{
|
|
idr_layer_cache = kmem_cache_create("idr_layer_cache",
|
|
sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
|
|
}
|
|
|
|
/**
|
|
* idr_init - initialize idr handle
|
|
* @idp: idr handle
|
|
*
|
|
* This function is use to set up the handle (@idp) that you will pass
|
|
* to the rest of the functions.
|
|
*/
|
|
void idr_init(struct idr *idp)
|
|
{
|
|
memset(idp, 0, sizeof(struct idr));
|
|
spin_lock_init(&idp->lock);
|
|
}
|
|
EXPORT_SYMBOL(idr_init);
|
|
|
|
static int idr_has_entry(int id, void *p, void *data)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
bool idr_is_empty(struct idr *idp)
|
|
{
|
|
return !idr_for_each(idp, idr_has_entry, NULL);
|
|
}
|
|
EXPORT_SYMBOL(idr_is_empty);
|
|
|
|
/**
|
|
* DOC: IDA description
|
|
* IDA - IDR based ID allocator
|
|
*
|
|
* This is id allocator without id -> pointer translation. Memory
|
|
* usage is much lower than full blown idr because each id only
|
|
* occupies a bit. ida uses a custom leaf node which contains
|
|
* IDA_BITMAP_BITS slots.
|
|
*
|
|
* 2007-04-25 written by Tejun Heo <htejun@gmail.com>
|
|
*/
|
|
|
|
static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (!ida->free_bitmap) {
|
|
spin_lock_irqsave(&ida->idr.lock, flags);
|
|
if (!ida->free_bitmap) {
|
|
ida->free_bitmap = bitmap;
|
|
bitmap = NULL;
|
|
}
|
|
spin_unlock_irqrestore(&ida->idr.lock, flags);
|
|
}
|
|
|
|
kfree(bitmap);
|
|
}
|
|
|
|
/**
|
|
* ida_pre_get - reserve resources for ida allocation
|
|
* @ida: ida handle
|
|
* @gfp_mask: memory allocation flag
|
|
*
|
|
* This function should be called prior to locking and calling the
|
|
* following function. It preallocates enough memory to satisfy the
|
|
* worst possible allocation.
|
|
*
|
|
* If the system is REALLY out of memory this function returns %0,
|
|
* otherwise %1.
|
|
*/
|
|
int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
|
|
{
|
|
/* allocate idr_layers */
|
|
if (!__idr_pre_get(&ida->idr, gfp_mask))
|
|
return 0;
|
|
|
|
/* allocate free_bitmap */
|
|
if (!ida->free_bitmap) {
|
|
struct ida_bitmap *bitmap;
|
|
|
|
bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
|
|
if (!bitmap)
|
|
return 0;
|
|
|
|
free_bitmap(ida, bitmap);
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(ida_pre_get);
|
|
|
|
/**
|
|
* ida_get_new_above - allocate new ID above or equal to a start id
|
|
* @ida: ida handle
|
|
* @starting_id: id to start search at
|
|
* @p_id: pointer to the allocated handle
|
|
*
|
|
* Allocate new ID above or equal to @starting_id. It should be called
|
|
* with any required locks.
|
|
*
|
|
* If memory is required, it will return %-EAGAIN, you should unlock
|
|
* and go back to the ida_pre_get() call. If the ida is full, it will
|
|
* return %-ENOSPC.
|
|
*
|
|
* @p_id returns a value in the range @starting_id ... %0x7fffffff.
|
|
*/
|
|
int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
|
|
{
|
|
struct idr_layer *pa[MAX_IDR_LEVEL + 1];
|
|
struct ida_bitmap *bitmap;
|
|
unsigned long flags;
|
|
int idr_id = starting_id / IDA_BITMAP_BITS;
|
|
int offset = starting_id % IDA_BITMAP_BITS;
|
|
int t, id;
|
|
|
|
restart:
|
|
/* get vacant slot */
|
|
t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
|
|
if (t < 0)
|
|
return t == -ENOMEM ? -EAGAIN : t;
|
|
|
|
if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
|
|
return -ENOSPC;
|
|
|
|
if (t != idr_id)
|
|
offset = 0;
|
|
idr_id = t;
|
|
|
|
/* if bitmap isn't there, create a new one */
|
|
bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
|
|
if (!bitmap) {
|
|
spin_lock_irqsave(&ida->idr.lock, flags);
|
|
bitmap = ida->free_bitmap;
|
|
ida->free_bitmap = NULL;
|
|
spin_unlock_irqrestore(&ida->idr.lock, flags);
|
|
|
|
if (!bitmap)
|
|
return -EAGAIN;
|
|
|
|
memset(bitmap, 0, sizeof(struct ida_bitmap));
|
|
rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
|
|
(void *)bitmap);
|
|
pa[0]->count++;
|
|
}
|
|
|
|
/* lookup for empty slot */
|
|
t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
|
|
if (t == IDA_BITMAP_BITS) {
|
|
/* no empty slot after offset, continue to the next chunk */
|
|
idr_id++;
|
|
offset = 0;
|
|
goto restart;
|
|
}
|
|
|
|
id = idr_id * IDA_BITMAP_BITS + t;
|
|
if (id >= MAX_IDR_BIT)
|
|
return -ENOSPC;
|
|
|
|
__set_bit(t, bitmap->bitmap);
|
|
if (++bitmap->nr_busy == IDA_BITMAP_BITS)
|
|
idr_mark_full(pa, idr_id);
|
|
|
|
*p_id = id;
|
|
|
|
/* Each leaf node can handle nearly a thousand slots and the
|
|
* whole idea of ida is to have small memory foot print.
|
|
* Throw away extra resources one by one after each successful
|
|
* allocation.
|
|
*/
|
|
if (ida->idr.id_free_cnt || ida->free_bitmap) {
|
|
struct idr_layer *p = get_from_free_list(&ida->idr);
|
|
if (p)
|
|
kmem_cache_free(idr_layer_cache, p);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(ida_get_new_above);
|
|
|
|
/**
|
|
* ida_remove - remove the given ID
|
|
* @ida: ida handle
|
|
* @id: ID to free
|
|
*/
|
|
void ida_remove(struct ida *ida, int id)
|
|
{
|
|
struct idr_layer *p = ida->idr.top;
|
|
int shift = (ida->idr.layers - 1) * IDR_BITS;
|
|
int idr_id = id / IDA_BITMAP_BITS;
|
|
int offset = id % IDA_BITMAP_BITS;
|
|
int n;
|
|
struct ida_bitmap *bitmap;
|
|
|
|
if (idr_id > idr_max(ida->idr.layers))
|
|
goto err;
|
|
|
|
/* clear full bits while looking up the leaf idr_layer */
|
|
while ((shift > 0) && p) {
|
|
n = (idr_id >> shift) & IDR_MASK;
|
|
__clear_bit(n, p->bitmap);
|
|
p = p->ary[n];
|
|
shift -= IDR_BITS;
|
|
}
|
|
|
|
if (p == NULL)
|
|
goto err;
|
|
|
|
n = idr_id & IDR_MASK;
|
|
__clear_bit(n, p->bitmap);
|
|
|
|
bitmap = (void *)p->ary[n];
|
|
if (!bitmap || !test_bit(offset, bitmap->bitmap))
|
|
goto err;
|
|
|
|
/* update bitmap and remove it if empty */
|
|
__clear_bit(offset, bitmap->bitmap);
|
|
if (--bitmap->nr_busy == 0) {
|
|
__set_bit(n, p->bitmap); /* to please idr_remove() */
|
|
idr_remove(&ida->idr, idr_id);
|
|
free_bitmap(ida, bitmap);
|
|
}
|
|
|
|
return;
|
|
|
|
err:
|
|
WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
|
|
}
|
|
EXPORT_SYMBOL(ida_remove);
|
|
|
|
/**
|
|
* ida_destroy - release all cached layers within an ida tree
|
|
* @ida: ida handle
|
|
*/
|
|
void ida_destroy(struct ida *ida)
|
|
{
|
|
idr_destroy(&ida->idr);
|
|
kfree(ida->free_bitmap);
|
|
}
|
|
EXPORT_SYMBOL(ida_destroy);
|
|
|
|
/**
|
|
* ida_simple_get - get a new id.
|
|
* @ida: the (initialized) ida.
|
|
* @start: the minimum id (inclusive, < 0x8000000)
|
|
* @end: the maximum id (exclusive, < 0x8000000 or 0)
|
|
* @gfp_mask: memory allocation flags
|
|
*
|
|
* Allocates an id in the range start <= id < end, or returns -ENOSPC.
|
|
* On memory allocation failure, returns -ENOMEM.
|
|
*
|
|
* Use ida_simple_remove() to get rid of an id.
|
|
*/
|
|
int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
|
|
gfp_t gfp_mask)
|
|
{
|
|
int ret, id;
|
|
unsigned int max;
|
|
unsigned long flags;
|
|
|
|
BUG_ON((int)start < 0);
|
|
BUG_ON((int)end < 0);
|
|
|
|
if (end == 0)
|
|
max = 0x80000000;
|
|
else {
|
|
BUG_ON(end < start);
|
|
max = end - 1;
|
|
}
|
|
|
|
again:
|
|
if (!ida_pre_get(ida, gfp_mask))
|
|
return -ENOMEM;
|
|
|
|
spin_lock_irqsave(&simple_ida_lock, flags);
|
|
ret = ida_get_new_above(ida, start, &id);
|
|
if (!ret) {
|
|
if (id > max) {
|
|
ida_remove(ida, id);
|
|
ret = -ENOSPC;
|
|
} else {
|
|
ret = id;
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&simple_ida_lock, flags);
|
|
|
|
if (unlikely(ret == -EAGAIN))
|
|
goto again;
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(ida_simple_get);
|
|
|
|
/**
|
|
* ida_simple_remove - remove an allocated id.
|
|
* @ida: the (initialized) ida.
|
|
* @id: the id returned by ida_simple_get.
|
|
*/
|
|
void ida_simple_remove(struct ida *ida, unsigned int id)
|
|
{
|
|
unsigned long flags;
|
|
|
|
BUG_ON((int)id < 0);
|
|
spin_lock_irqsave(&simple_ida_lock, flags);
|
|
ida_remove(ida, id);
|
|
spin_unlock_irqrestore(&simple_ida_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(ida_simple_remove);
|
|
|
|
/**
|
|
* ida_init - initialize ida handle
|
|
* @ida: ida handle
|
|
*
|
|
* This function is use to set up the handle (@ida) that you will pass
|
|
* to the rest of the functions.
|
|
*/
|
|
void ida_init(struct ida *ida)
|
|
{
|
|
memset(ida, 0, sizeof(struct ida));
|
|
idr_init(&ida->idr);
|
|
|
|
}
|
|
EXPORT_SYMBOL(ida_init);
|