diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2020-02-06 23:49:13 +0300 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2020-02-07 13:55:49 +0300 |
| commit | f14f27b1663269a81ed62d3961fe70250a1a0623 (patch) | |
| tree | 0baf403e36a0fef1778f040ed100c22d2547fbfa /drivers/gpu/drm/i915/i915_scheduler.c | |
| parent | f91d8156ab8afb32447cd2bf3189219bab943f18 (diff) | |
| download | linux-f14f27b1663269a81ed62d3961fe70250a1a0623.tar.xz | |
drm/i915/gt: Protect defer_request() from new waiters
Mika spotted
<4>[17436.705441] general protection fault: 0000 [#1] PREEMPT SMP PTI
<4>[17436.705447] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.5.0+ #1
<4>[17436.705449] Hardware name: System manufacturer System Product Name/Z170M-PLUS, BIOS 3805 05/16/2018
<4>[17436.705512] RIP: 0010:__execlists_submission_tasklet+0xc4d/0x16e0 [i915]
<4>[17436.705516] Code: c5 4c 8d 60 e0 75 17 e9 8c 07 00 00 49 8b 44 24 20 49 39 c5 4c 8d 60 e0 0f 84 7a 07 00 00 49 8b 5c 24 08 49 8b 87 80 00 00 00 <48> 39 83 d8 fe ff ff 75 d9 48 8b 83 88 fe ff ff a8 01 0f 84 b6 05
<4>[17436.705518] RSP: 0018:ffffc9000012ce80 EFLAGS: 00010083
<4>[17436.705521] RAX: ffff88822ae42000 RBX: 5a5a5a5a5a5a5a5a RCX: dead000000000122
<4>[17436.705523] RDX: ffff88822ae42588 RSI: ffff8881e32a7908 RDI: ffff8881c429fd48
<4>[17436.705525] RBP: ffffc9000012cf00 R08: ffff88822ae42588 R09: 00000000fffffffe
<4>[17436.705527] R10: ffff8881c429fb80 R11: 00000000a677cf08 R12: ffff8881c42a0aa8
<4>[17436.705529] R13: ffff8881c429fd38 R14: ffff88822ae42588 R15: ffff8881c429fb80
<4>[17436.705532] FS: 0000000000000000(0000) GS:ffff88822ed00000(0000) knlGS:0000000000000000
<4>[17436.705534] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[17436.705536] CR2: 00007f858c76d000 CR3: 0000000005610003 CR4: 00000000003606e0
<4>[17436.705538] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
<4>[17436.705540] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
<4>[17436.705542] Call Trace:
<4>[17436.705545] <IRQ>
<4>[17436.705603] execlists_submission_tasklet+0xc0/0x130 [i915]
which is us consuming a partially initialised new waiter in
defer_requests(). We can prevent this by initialising the i915_dependency
prior to making it visible, and since we are using a concurrent
list_add/iterator mark them up to the compiler.
Fixes: 8ee36e048c98 ("drm/i915/execlists: Minimalistic timeslicing")
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/20200206204915.2636606-2-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/i915_scheduler.c')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_scheduler.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c index 5d96cfba40f8..34b654b4e58a 100644 --- a/drivers/gpu/drm/i915/i915_scheduler.c +++ b/drivers/gpu/drm/i915/i915_scheduler.c @@ -423,8 +423,6 @@ bool __i915_sched_node_add_dependency(struct i915_sched_node *node, if (!node_signaled(signal)) { INIT_LIST_HEAD(&dep->dfs_link); - list_add(&dep->wait_link, &signal->waiters_list); - list_add(&dep->signal_link, &node->signalers_list); dep->signaler = signal; dep->waiter = node; dep->flags = flags; @@ -434,6 +432,10 @@ bool __i915_sched_node_add_dependency(struct i915_sched_node *node, !node_started(signal)) node->flags |= I915_SCHED_HAS_SEMAPHORE_CHAIN; + /* All set, now publish. Beware the lockless walkers. */ + list_add(&dep->signal_link, &node->signalers_list); + list_add_rcu(&dep->wait_link, &signal->waiters_list); + /* * As we do not allow WAIT to preempt inflight requests, * once we have executed a request, along with triggering |