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drm/panthor: Replace sleep locks with spinlocks in fdinfo path

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Commit 0590c94c35 ("drm/panthor: Fix race condition when gathering fdinfo
group samples") introduced an xarray lock to deal with potential
use-after-free errors when accessing groups fdinfo figures. However, this
toggles the kernel's atomic context status, so the next nested mutex lock
will raise a warning when the kernel is compiled with mutex debug options:

CONFIG_DEBUG_RT_MUTEXES=y
CONFIG_DEBUG_MUTEXES=y

Replace Panthor's group fdinfo data mutex with a guarded spinlock.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Fixes: 0590c94c35 ("drm/panthor: Fix race condition when gathering fdinfo group samples")
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250303190923.1639985-1-adrian.larumbe@collabora.com
This commit is contained in:
Adrián Larumbe 2025-03-03 19:08:45 +00:00 committed by Steven Price
parent e4c0fd3f96
commit e379856b42
1 changed files with 12 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
drivers/gpu/drm/panthor/panthor_sched.c
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@ -9,6 +9,7 @@
#include <drm/panthor_drm.h>
#include <linux/build_bug.h>
#include <linux/cleanup.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
@ -631,10 +632,10 @@ struct panthor_group {
struct panthor_gpu_usage data;
/**
* @lock: Mutex to govern concurrent access from drm file's fdinfo callback
* and job post-completion processing function
* @fdinfo.lock: Spinlock to govern concurrent access from drm file's fdinfo
* callback and job post-completion processing function
*/
struct mutex lock;
spinlock_t lock;
/** @fdinfo.kbo_sizes: Aggregate size of private kernel BO's held by the group. */
size_t kbo_sizes;
@ -910,8 +911,6 @@ static void group_release_work(struct work_struct *work)
release_work);
u32 i;
mutex_destroy(&group->fdinfo.lock);
for (i = 0; i < group->queue_count; i++)
group_free_queue(group, group->queues[i]);
@ -2861,12 +2860,12 @@ static void update_fdinfo_stats(struct panthor_job *job)
struct panthor_job_profiling_data *slots = queue->profiling.slots->kmap;
struct panthor_job_profiling_data *data = &slots[job->profiling.slot];
mutex_lock(&group->fdinfo.lock);
if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_CYCLES)
fdinfo->cycles += data->cycles.after - data->cycles.before;
if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_TIMESTAMP)
fdinfo->time += data->time.after - data->time.before;
mutex_unlock(&group->fdinfo.lock);
scoped_guard(spinlock, &group->fdinfo.lock) {
if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_CYCLES)
fdinfo->cycles += data->cycles.after - data->cycles.before;
if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_TIMESTAMP)
fdinfo->time += data->time.after - data->time.before;
}
}
void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile)
@ -2880,12 +2879,11 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile)
xa_lock(&gpool->xa);
xa_for_each(&gpool->xa, i, group) {
mutex_lock(&group->fdinfo.lock);
guard(spinlock)(&group->fdinfo.lock);
pfile->stats.cycles += group->fdinfo.data.cycles;
pfile->stats.time += group->fdinfo.data.time;
group->fdinfo.data.cycles = 0;
group->fdinfo.data.time = 0;
mutex_unlock(&group->fdinfo.lock);
}
xa_unlock(&gpool->xa);
}
@ -3537,7 +3535,7 @@ int panthor_group_create(struct panthor_file *pfile,
mutex_unlock(&sched->reset.lock);
add_group_kbo_sizes(group->ptdev, group);
mutex_init(&group->fdinfo.lock);
spin_lock_init(&group->fdinfo.lock);
return gid;