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scsi: storvsc: Re-init stor_chns when a channel interrupt is re-assigned 

For each storvsc_device, storvsc keeps track of the channel target CPUs
associated to the device (alloced_cpus) and it uses this information to
fill a "cache" (stor_chns) mapping CPU->channel according to a certain
heuristic.  Update the alloced_cpus mask and the stor_chns array when a
channel of the storvsc device is re-assigned to a different CPU.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: <linux-scsi@vger.kernel.org>
Link: https://lore.kernel.org/r/20200406001514.19876-12-parri.andrea@gmail.com
Reviewed-by; Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
[ wei: fix a small issue reported by kbuild test robot <lkp@intel.com> ]
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Andrea Parri (Microsoft) 2020-04-06 02:15:14 +02:00 committed by Wei Liu
parent 7527810573
commit 7769e18c20
3 changed files with 95 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/hv/vmbus_drv.c
View File

@ -1777,6 +1777,10 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel,
* in on a CPU that is different from the channel target_cpu value.
*/
if (channel->change_target_cpu_callback)
(*channel->change_target_cpu_callback)(channel,
channel->target_cpu, target_cpu);
channel->target_cpu = target_cpu;
channel->target_vp = hv_cpu_number_to_vp_number(target_cpu);
channel->numa_node = cpu_to_node(target_cpu);

96
drivers/scsi/storvsc_drv.c
View File

@ -621,6 +621,64 @@ get_in_err:
}
static void storvsc_change_target_cpu(struct vmbus_channel *channel, u32 old,
u32 new)
{
struct storvsc_device *stor_device;
struct vmbus_channel *cur_chn;
bool old_is_alloced = false;
struct hv_device *device;
unsigned long flags;
int cpu;
device = channel->primary_channel ?
channel->primary_channel->device_obj
: channel->device_obj;
stor_device = get_out_stor_device(device);
if (!stor_device)
return;
/* See storvsc_do_io() -> get_og_chn(). */
spin_lock_irqsave(&device->channel->lock, flags);
/*
* Determines if the storvsc device has other channels assigned to
* the "old" CPU to update the alloced_cpus mask and the stor_chns
* array.
*/
if (device->channel != channel && device->channel->target_cpu == old) {
cur_chn = device->channel;
old_is_alloced = true;
goto old_is_alloced;
}
list_for_each_entry(cur_chn, &device->channel->sc_list, sc_list) {
if (cur_chn == channel)
continue;
if (cur_chn->target_cpu == old) {
old_is_alloced = true;
goto old_is_alloced;
}
}
old_is_alloced:
if (old_is_alloced)
WRITE_ONCE(stor_device->stor_chns[old], cur_chn);
else
cpumask_clear_cpu(old, &stor_device->alloced_cpus);
/* "Flush" the stor_chns array. */
for_each_possible_cpu(cpu) {
if (stor_device->stor_chns[cpu] && !cpumask_test_cpu(
cpu, &stor_device->alloced_cpus))
WRITE_ONCE(stor_device->stor_chns[cpu], NULL);
}
WRITE_ONCE(stor_device->stor_chns[new], channel);
cpumask_set_cpu(new, &stor_device->alloced_cpus);
spin_unlock_irqrestore(&device->channel->lock, flags);
}
static void handle_sc_creation(struct vmbus_channel *new_sc)
{
struct hv_device *device = new_sc->primary_channel->device_obj;
@ -648,6 +706,8 @@ static void handle_sc_creation(struct vmbus_channel *new_sc)
return;
}
new_sc->change_target_cpu_callback = storvsc_change_target_cpu;
/* Add the sub-channel to the array of available channels. */
stor_device->stor_chns[new_sc->target_cpu] = new_sc;
cpumask_set_cpu(new_sc->target_cpu, &stor_device->alloced_cpus);
@ -876,6 +936,8 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
if (stor_device->stor_chns == NULL)
return -ENOMEM;
device->channel->change_target_cpu_callback = storvsc_change_target_cpu;
stor_device->stor_chns[device->channel->target_cpu] = device->channel;
cpumask_set_cpu(device->channel->target_cpu,
&stor_device->alloced_cpus);
@ -1248,8 +1310,10 @@ static struct vmbus_channel *get_og_chn(struct storvsc_device *stor_device,
const struct cpumask *node_mask;
int num_channels, tgt_cpu;
if (stor_device->num_sc == 0)
if (stor_device->num_sc == 0) {
stor_device->stor_chns[q_num] = stor_device->device->channel;
return stor_device->device->channel;
}
/*
* Our channel array is sparsley populated and we
@ -1258,7 +1322,6 @@ static struct vmbus_channel *get_og_chn(struct storvsc_device *stor_device,
* The strategy is simple:
* I. Ensure NUMA locality
* II. Distribute evenly (best effort)
* III. Mapping is persistent.
*/
node_mask = cpumask_of_node(cpu_to_node(q_num));
@ -1268,8 +1331,10 @@ static struct vmbus_channel *get_og_chn(struct storvsc_device *stor_device,
if (cpumask_test_cpu(tgt_cpu, node_mask))
num_channels++;
}
if (num_channels == 0)
if (num_channels == 0) {
stor_device->stor_chns[q_num] = stor_device->device->channel;
return stor_device->device->channel;
}
hash_qnum = q_num;
while (hash_qnum >= num_channels)
@ -1295,6 +1360,7 @@ static int storvsc_do_io(struct hv_device *device,
struct storvsc_device *stor_device;
struct vstor_packet *vstor_packet;
struct vmbus_channel *outgoing_channel, *channel;
unsigned long flags;
int ret = 0;
const struct cpumask *node_mask;
int tgt_cpu;
@ -1308,10 +1374,11 @@ static int storvsc_do_io(struct hv_device *device,
request->device = device;
/*
* Select an an appropriate channel to send the request out.
* Select an appropriate channel to send the request out.
*/
if (stor_device->stor_chns[q_num] != NULL) {
outgoing_channel = stor_device->stor_chns[q_num];
/* See storvsc_change_target_cpu(). */
outgoing_channel = READ_ONCE(stor_device->stor_chns[q_num]);
if (outgoing_channel != NULL) {
if (outgoing_channel->target_cpu == q_num) {
/*
* Ideally, we want to pick a different channel if
@ -1324,7 +1391,10 @@ static int storvsc_do_io(struct hv_device *device,
continue;
if (tgt_cpu == q_num)
continue;
channel = stor_device->stor_chns[tgt_cpu];
channel = READ_ONCE(
stor_device->stor_chns[tgt_cpu]);
if (channel == NULL)
continue;
if (hv_get_avail_to_write_percent(
&channel->outbound)
> ring_avail_percent_lowater) {
@ -1350,7 +1420,10 @@ static int storvsc_do_io(struct hv_device *device,
for_each_cpu(tgt_cpu, &stor_device->alloced_cpus) {
if (cpumask_test_cpu(tgt_cpu, node_mask))
continue;
channel = stor_device->stor_chns[tgt_cpu];
channel = READ_ONCE(
stor_device->stor_chns[tgt_cpu]);
if (channel == NULL)
continue;
if (hv_get_avail_to_write_percent(
&channel->outbound)
> ring_avail_percent_lowater) {
@ -1360,7 +1433,14 @@ static int storvsc_do_io(struct hv_device *device,
}
}
} else {
spin_lock_irqsave(&device->channel->lock, flags);
outgoing_channel = stor_device->stor_chns[q_num];
if (outgoing_channel != NULL) {
spin_unlock_irqrestore(&device->channel->lock, flags);
goto found_channel;
}
outgoing_channel = get_og_chn(stor_device, q_num);
spin_unlock_irqrestore(&device->channel->lock, flags);
}
found_channel:

3
include/linux/hyperv.h
View File

@ -773,6 +773,9 @@ struct vmbus_channel {
void (*onchannel_callback)(void *context);
void *channel_callback_context;
void (*change_target_cpu_callback)(struct vmbus_channel *channel,
u32 old, u32 new);
/*
* Synchronize channel scheduling and channel removal; see the inline
* comments in vmbus_chan_sched() and vmbus_reset_channel_cb().