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A couple clk driver fixes, a build fix, and a deadlock fix. 

- Mediatek mt7988 has broken PCIe because the wrong parent is used
 
  - Mediatek clk drivers may deadlock when registering their clks because
    the clk provider device is repeatedly runtime PM resumed and
    suspended during probe and clk registration. Resuming the clk
    provider device deadlocks with an ABBA deadlock due to genpd_lock and
    the clk prepare_lock. The fix is to keep the device runtime resumed
    while registering clks.
 
  - Another runtime PM related deadlock, this time with disabling unused
    clks during late init. We get an ABBA deadlock where a device is
    runtime PM resuming (or suspending) while the disabling of unused
    clks is happening in parallel. That runtime PM action calls into the
    clk framework and tries to grab the clk prepare_lock while the
    disabling of unused clks holds the prepare_lock and is waiting for
    that runtime PM action to complete. The fix is to runtime resume all
    the clk provider devices before grabbing the clk prepare_lock during
    disable unused.
 
  - A build fix to provide an empty devm_clk_rate_exclusive_get()
    function when CONFIG_COMMON_CLK=n
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Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux

Pull clk fixes from Stephen Boyd:
 "A couple clk driver fixes, a build fix, and a deadlock fix:

   - Mediatek mt7988 has broken PCIe because the wrong parent is used

   - Mediatek clk drivers may deadlock when registering their clks
     because the clk provider device is repeatedly runtime PM resumed
     and suspended during probe and clk registration.

     Resuming the clk provider device deadlocks with an ABBA deadlock
     due to genpd_lock and the clk prepare_lock. The fix is to keep the
     device runtime resumed while registering clks.

   - Another runtime PM related deadlock, this time with disabling
     unused clks during late init.

     We get an ABBA deadlock where a device is runtime PM resuming (or
     suspending) while the disabling of unused clks is happening in
     parallel. That runtime PM action calls into the clk framework and
     tries to grab the clk prepare_lock while the disabling of unused
     clks holds the prepare_lock and is waiting for that runtime PM
     action to complete.

     The fix is to runtime resume all the clk provider devices before
     grabbing the clk prepare_lock during disable unused.

   - A build fix to provide an empty devm_clk_rate_exclusive_get()
     function when CONFIG_COMMON_CLK=n"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: mediatek: mt7988-infracfg: fix clocks for 2nd PCIe port
  clk: mediatek: Do a runtime PM get on controllers during probe
  clk: Get runtime PM before walking tree for clk_summary
  clk: Get runtime PM before walking tree during disable_unused
  clk: Initialize struct clk_core kref earlier
  clk: Don't hold prepare_lock when calling kref_put()
  clk: Remove prepare_lock hold assertion in __clk_release()
  clk: Provide !COMMON_CLK dummy for devm_clk_rate_exclusive_get()
This commit is contained in:
Linus Torvalds 2024-04-20 10:36:02 -07:00
parent 13a2e429f6 d3e8a91a84
commit 560d4e7738
4 changed files with 156 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

173
drivers/clk/clk.c
View File

@ -37,6 +37,10 @@ static HLIST_HEAD(clk_root_list);
static HLIST_HEAD(clk_orphan_list);
static LIST_HEAD(clk_notifier_list);
/* List of registered clks that use runtime PM */
static HLIST_HEAD(clk_rpm_list);
static DEFINE_MUTEX(clk_rpm_list_lock);
static const struct hlist_head *all_lists[] = {
&clk_root_list,
&clk_orphan_list,
@ -59,6 +63,7 @@ struct clk_core {
struct clk_hw *hw;
struct module *owner;
struct device *dev;
struct hlist_node rpm_node;
struct device_node *of_node;
struct clk_core *parent;
struct clk_parent_map *parents;
@ -122,6 +127,89 @@ static void clk_pm_runtime_put(struct clk_core *core)
pm_runtime_put_sync(core->dev);
}
/**
* clk_pm_runtime_get_all() - Runtime "get" all clk provider devices
*
* Call clk_pm_runtime_get() on all runtime PM enabled clks in the clk tree so
* that disabling unused clks avoids a deadlock where a device is runtime PM
* resuming/suspending and the runtime PM callback is trying to grab the
* prepare_lock for something like clk_prepare_enable() while
* clk_disable_unused_subtree() holds the prepare_lock and is trying to runtime
* PM resume/suspend the device as well.
*
* Context: Acquires the 'clk_rpm_list_lock' and returns with the lock held on
* success. Otherwise the lock is released on failure.
*
* Return: 0 on success, negative errno otherwise.
*/
static int clk_pm_runtime_get_all(void)
{
int ret;
struct clk_core *core, *failed;
/*
* Grab the list lock to prevent any new clks from being registered
* or unregistered until clk_pm_runtime_put_all().
*/
mutex_lock(&clk_rpm_list_lock);
/*
* Runtime PM "get" all the devices that are needed for the clks
* currently registered. Do this without holding the prepare_lock, to
* avoid the deadlock.
*/
hlist_for_each_entry(core, &clk_rpm_list, rpm_node) {
ret = clk_pm_runtime_get(core);
if (ret) {
failed = core;
pr_err("clk: Failed to runtime PM get '%s' for clk '%s'\n",
dev_name(failed->dev), failed->name);
goto err;
}
}
return 0;
err:
hlist_for_each_entry(core, &clk_rpm_list, rpm_node) {
if (core == failed)
break;
clk_pm_runtime_put(core);
}
mutex_unlock(&clk_rpm_list_lock);
return ret;
}
/**
* clk_pm_runtime_put_all() - Runtime "put" all clk provider devices
*
* Put the runtime PM references taken in clk_pm_runtime_get_all() and release
* the 'clk_rpm_list_lock'.
*/
static void clk_pm_runtime_put_all(void)
{
struct clk_core *core;
hlist_for_each_entry(core, &clk_rpm_list, rpm_node)
clk_pm_runtime_put(core);
mutex_unlock(&clk_rpm_list_lock);
}
static void clk_pm_runtime_init(struct clk_core *core)
{
struct device *dev = core->dev;
if (dev && pm_runtime_enabled(dev)) {
core->rpm_enabled = true;
mutex_lock(&clk_rpm_list_lock);
hlist_add_head(&core->rpm_node, &clk_rpm_list);
mutex_unlock(&clk_rpm_list_lock);
}
}
/*** locking ***/
static void clk_prepare_lock(void)
{
@ -1381,9 +1469,6 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
if (core->flags & CLK_IGNORE_UNUSED)
return;
if (clk_pm_runtime_get(core))
return;
if (clk_core_is_prepared(core)) {
trace_clk_unprepare(core);
if (core->ops->unprepare_unused)
@ -1392,8 +1477,6 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
core->ops->unprepare(core->hw);
trace_clk_unprepare_complete(core);
}
clk_pm_runtime_put(core);
}
static void __init clk_disable_unused_subtree(struct clk_core *core)
@ -1409,9 +1492,6 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
if (core->flags & CLK_OPS_PARENT_ENABLE)
clk_core_prepare_enable(core->parent);
if (clk_pm_runtime_get(core))
goto unprepare_out;
flags = clk_enable_lock();
if (core->enable_count)
@ -1436,8 +1516,6 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
unlock_out:
clk_enable_unlock(flags);
clk_pm_runtime_put(core);
unprepare_out:
if (core->flags & CLK_OPS_PARENT_ENABLE)
clk_core_disable_unprepare(core->parent);
}
@ -1453,6 +1531,7 @@ __setup("clk_ignore_unused", clk_ignore_unused_setup);
static int __init clk_disable_unused(void)
{
struct clk_core *core;
int ret;
if (clk_ignore_unused) {
pr_warn("clk: Not disabling unused clocks\n");
@ -1461,6 +1540,13 @@ static int __init clk_disable_unused(void)
pr_info("clk: Disabling unused clocks\n");
ret = clk_pm_runtime_get_all();
if (ret)
return ret;
/*
* Grab the prepare lock to keep the clk topology stable while iterating
* over clks.
*/
clk_prepare_lock();
hlist_for_each_entry(core, &clk_root_list, child_node)
@ -1477,6 +1563,8 @@ static int __init clk_disable_unused(void)
clk_prepare_unlock();
clk_pm_runtime_put_all();
return 0;
}
late_initcall_sync(clk_disable_unused);
@ -3252,9 +3340,7 @@ static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c,
{
struct clk_core *child;
clk_pm_runtime_get(c);
clk_summary_show_one(s, c, level);
clk_pm_runtime_put(c);
hlist_for_each_entry(child, &c->children, child_node)
clk_summary_show_subtree(s, child, level + 1);
@ -3264,11 +3350,15 @@ static int clk_summary_show(struct seq_file *s, void *data)
{
struct clk_core *c;
struct hlist_head **lists = s->private;
int ret;
seq_puts(s, " enable prepare protect duty hardware connection\n");
seq_puts(s, " clock count count count rate accuracy phase cycle enable consumer id\n");
seq_puts(s, "---------------------------------------------------------------------------------------------------------------------------------------------\n");
ret = clk_pm_runtime_get_all();
if (ret)
return ret;
clk_prepare_lock();
@ -3277,6 +3367,7 @@ static int clk_summary_show(struct seq_file *s, void *data)
clk_summary_show_subtree(s, c, 0);
clk_prepare_unlock();
clk_pm_runtime_put_all();
return 0;
}
@ -3324,8 +3415,14 @@ static int clk_dump_show(struct seq_file *s, void *data)
struct clk_core *c;
bool first_node = true;
struct hlist_head **lists = s->private;
int ret;
ret = clk_pm_runtime_get_all();
if (ret)
return ret;
seq_putc(s, '{');
clk_prepare_lock();
for (; *lists; lists++) {
@ -3338,6 +3435,7 @@ static int clk_dump_show(struct seq_file *s, void *data)
}
clk_prepare_unlock();
clk_pm_runtime_put_all();
seq_puts(s, "}\n");
return 0;
@ -3981,8 +4079,6 @@ static int __clk_core_init(struct clk_core *core)
}
clk_core_reparent_orphans_nolock();
kref_init(&core->ref);
out:
clk_pm_runtime_put(core);
unlock:
@ -4211,6 +4307,22 @@ static void clk_core_free_parent_map(struct clk_core *core)
kfree(core->parents);
}
/* Free memory allocated for a struct clk_core */
static void __clk_release(struct kref *ref)
{
struct clk_core *core = container_of(ref, struct clk_core, ref);
if (core->rpm_enabled) {
mutex_lock(&clk_rpm_list_lock);
hlist_del(&core->rpm_node);
mutex_unlock(&clk_rpm_list_lock);
}
clk_core_free_parent_map(core);
kfree_const(core->name);
kfree(core);
}
static struct clk *
__clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
{
@ -4231,6 +4343,8 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
goto fail_out;
}
kref_init(&core->ref);
core->name = kstrdup_const(init->name, GFP_KERNEL);
if (!core->name) {
ret = -ENOMEM;
@ -4243,9 +4357,8 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
}
core->ops = init->ops;
if (dev && pm_runtime_enabled(dev))
core->rpm_enabled = true;
core->dev = dev;
clk_pm_runtime_init(core);
core->of_node = np;
if (dev && dev->driver)
core->owner = dev->driver->owner;
@ -4285,12 +4398,10 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
hw->clk = NULL;
fail_create_clk:
clk_core_free_parent_map(core);
fail_parents:
fail_ops:
kfree_const(core->name);
fail_name:
kfree(core);
kref_put(&core->ref, __clk_release);
fail_out:
return ERR_PTR(ret);
}
@ -4370,18 +4481,6 @@ int of_clk_hw_register(struct device_node *node, struct clk_hw *hw)
}
EXPORT_SYMBOL_GPL(of_clk_hw_register);
/* Free memory allocated for a clock. */
static void __clk_release(struct kref *ref)
{
struct clk_core *core = container_of(ref, struct clk_core, ref);
lockdep_assert_held(&prepare_lock);
clk_core_free_parent_map(core);
kfree_const(core->name);
kfree(core);
}
/*
* Empty clk_ops for unregistered clocks. These are used temporarily
* after clk_unregister() was called on a clock and until last clock
@ -4472,7 +4571,8 @@ void clk_unregister(struct clk *clk)
if (ops == &clk_nodrv_ops) {
pr_err("%s: unregistered clock: %s\n", __func__,
clk->core->name);
goto unlock;
clk_prepare_unlock();
return;
}
/*
* Assign empty clock ops for consumers that might still hold
@ -4506,11 +4606,10 @@ void clk_unregister(struct clk *clk)
if (clk->core->protect_count)
pr_warn("%s: unregistering protected clock: %s\n",
__func__, clk->core->name);
clk_prepare_unlock();
kref_put(&clk->core->ref, __clk_release);
free_clk(clk);
unlock:
clk_prepare_unlock();
}
EXPORT_SYMBOL_GPL(clk_unregister);
@ -4669,13 +4768,11 @@ void __clk_put(struct clk *clk)
if (clk->min_rate > 0 || clk->max_rate < ULONG_MAX)
clk_set_rate_range_nolock(clk, 0, ULONG_MAX);
owner = clk->core->owner;
kref_put(&clk->core->ref, __clk_release);
clk_prepare_unlock();
owner = clk->core->owner;
kref_put(&clk->core->ref, __clk_release);
module_put(owner);
free_clk(clk);
}

2
drivers/clk/mediatek/clk-mt7988-infracfg.c
View File

@ -156,7 +156,7 @@ static const struct mtk_gate infra_clks[] = {
GATE_INFRA0(CLK_INFRA_PCIE_PERI_26M_CK_P1, "infra_pcie_peri_ck_26m_ck_p1",
"csw_infra_f26m_sel", 8),
GATE_INFRA0(CLK_INFRA_PCIE_PERI_26M_CK_P2, "infra_pcie_peri_ck_26m_ck_p2",
"csw_infra_f26m_sel", 9),
"infra_pcie_peri_ck_26m_ck_p3", 9),
GATE_INFRA0(CLK_INFRA_PCIE_PERI_26M_CK_P3, "infra_pcie_peri_ck_26m_ck_p3",
"csw_infra_f26m_sel", 10),
/* INFRA1 */

15
drivers/clk/mediatek/clk-mtk.c
View File

@ -13,6 +13,7 @@
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include "clk-mtk.h"
@ -494,6 +495,16 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
return IS_ERR(base) ? PTR_ERR(base) : -ENOMEM;
}
devm_pm_runtime_enable(&pdev->dev);
/*
* Do a pm_runtime_resume_and_get() to workaround a possible
* deadlock between clk_register() and the genpd framework.
*/
r = pm_runtime_resume_and_get(&pdev->dev);
if (r)
return r;
/* Calculate how many clk_hw_onecell_data entries to allocate */
num_clks = mcd->num_clks + mcd->num_composite_clks;
num_clks += mcd->num_fixed_clks + mcd->num_factor_clks;
@ -574,6 +585,8 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
goto unregister_clks;
}
pm_runtime_put(&pdev->dev);
return r;
unregister_clks:
@ -604,6 +617,8 @@ free_data:
free_base:
if (mcd->shared_io && base)
iounmap(base);
pm_runtime_put(&pdev->dev);
return r;
}

5
include/linux/clk.h
View File

@ -286,6 +286,11 @@ static inline int clk_rate_exclusive_get(struct clk *clk)
return 0;
}
static inline int devm_clk_rate_exclusive_get(struct device *dev, struct clk *clk)
{
return 0;
}
static inline void clk_rate_exclusive_put(struct clk *clk) {}
#endif