diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2020-03-09 18:05:40 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2020-03-09 21:38:57 +0100 |
| commit | f494960d5ee79e909214560c6b64b245fbe6c230 (patch) | |
| tree | ed374bf299d0a795e41da6bcd7475e47b228b30b | |
| parent | drm/i915: Lock gmbus/aux mutexes while changing cdclk (diff) | |
| download | linux-f494960d5ee79e909214560c6b64b245fbe6c230.tar.xz linux-f494960d5ee79e909214560c6b64b245fbe6c230.zip | |
drm/i915/gt: Defend against concurrent updates to execlists->active
[ 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
| -rw-r--r-- | drivers/gpu/drm/i915/gt/intel_engine.h | 15 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/gt/intel_lrc.c | 13 |
2 files changed, 22 insertions, 6 deletions
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h index 29c8c03c5caa..b469de0dd9b6 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine.h +++ b/drivers/gpu/drm/i915/gt/intel_engine.h @@ -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 diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 4a1d1c599124..0604b11a2842 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -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 { |