mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-07 11:33:58 -04:00
Code Issues Packages Projects Releases Wiki Activity

drm/i915/gt: Defend against concurrent updates to execlists->active

Browse Source 
[  206.875637] BUG: KCSAN: data-race in __i915_schedule+0x7fc/0x930 [i915]
[  206.875654]
[  206.875666] race at unknown origin, with read to 0xffff8881f7644480 of 8 bytes by task 703 on cpu 3:
[  206.875901]  __i915_schedule+0x7fc/0x930 [i915]
[  206.876130]  __bump_priority+0x63/0x80 [i915]
[  206.876361]  __i915_sched_node_add_dependency+0x258/0x300 [i915]
[  206.876593]  i915_sched_node_add_dependency+0x50/0xa0 [i915]
[  206.876824]  i915_request_await_dma_fence+0x1da/0x530 [i915]
[  206.877057]  i915_request_await_object+0x2fe/0x470 [i915]
[  206.877287]  i915_gem_do_execbuffer+0x45dc/0x4c20 [i915]
[  206.877517]  i915_gem_execbuffer2_ioctl+0x2c3/0x580 [i915]
[  206.877535]  drm_ioctl_kernel+0xe4/0x120
[  206.877549]  drm_ioctl+0x297/0x4c7
[  206.877563]  ksys_ioctl+0x89/0xb0
[  206.877577]  __x64_sys_ioctl+0x42/0x60
[  206.877591]  do_syscall_64+0x6e/0x2c0
[  206.877606]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

v2: Be safe and include mb

References: https://gitlab.freedesktop.org/drm/intel/issues/1318
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200309170540.10332-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson
2020-03-09 17:05:40 +00:00
parent bb9ca240dc
commit f494960d5e
2 changed files with 22 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
drivers/gpu/drm/i915/gt/intel_engine.h
View File

@@ -107,7 +107,20 @@ execlists_num_ports(const struct intel_engine_execlists * const execlists)
static inline struct i915_request *
execlists_active(const struct intel_engine_execlists *execlists)
{
return *READ_ONCE(execlists->active);
struct i915_request * const *cur, * const *old, *active;
cur = READ_ONCE(execlists->active);
smp_rmb(); /* pairs with overwrite protection in process_csb() */
do {
old = cur;
active = READ_ONCE(*cur);
cur = READ_ONCE(execlists->active);
smp_rmb(); /* and complete the seqlock retry */
} while (unlikely(cur != old));
return active;
}
static inline void

13
drivers/gpu/drm/i915/gt/intel_lrc.c
View File

@@ -2232,6 +2232,7 @@ cancel_port_requests(struct intel_engine_execlists * const execlists)
execlists_schedule_out(*port);
clear_ports(execlists->inflight, ARRAY_SIZE(execlists->inflight));
smp_wmb(); /* complete the seqlock for execlists_active() */
WRITE_ONCE(execlists->active, execlists->inflight);
}
@@ -2386,6 +2387,7 @@ static void process_csb(struct intel_engine_cs *engine)
/* Point active to the new ELSP; prevent overwriting */
WRITE_ONCE(execlists->active, execlists->pending);
smp_wmb(); /* notify execlists_active() */
/* cancel old inflight, prepare for switch */
trace_ports(execlists, "preempted", old);
@@ -2393,11 +2395,12 @@ static void process_csb(struct intel_engine_cs *engine)
execlists_schedule_out(*old++);
/* switch pending to inflight */
WRITE_ONCE(execlists->active,
memcpy(execlists->inflight,
execlists->pending,
execlists_num_ports(execlists) *
sizeof(*execlists->pending)));
memcpy(execlists->inflight,
execlists->pending,
execlists_num_ports(execlists) *
sizeof(*execlists->pending));
smp_wmb(); /* complete the seqlock */
WRITE_ONCE(execlists->active, execlists->inflight);
WRITE_ONCE(execlists->pending[0], NULL);
} else {