From 876adc56894da18cef59b92a0357cde7f5c58d73 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 9 Mar 2020 11:36:23 +0000
Subject: drm/i915/gt: Mark up intel_rps.active for racy reads
Git-commit: 74e5a9aca01e77ea3f5e4b7b1d010249d600ca0e
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
We read the current state of intel_rps.active outside of the lock, so
mark up the racy access.
[ 525.037073] BUG: KCSAN: data-race in intel_rps_boost [i915] / intel_rps_park [i915]
[ 525.037091]
[ 525.037103] write to 0xffff8881f145efa1 of 1 bytes by task 192 on cpu 2:
[ 525.037331] intel_rps_park+0x72/0x230 [i915]
[ 525.037552] __gt_park+0x61/0xa0 [i915]
[ 525.037771] ____intel_wakeref_put_last+0x42/0x90 [i915]
[ 525.037991] __intel_wakeref_put_work+0xd3/0xf0 [i915]
[ 525.038008] process_one_work+0x3b1/0x690
[ 525.038022] worker_thread+0x80/0x670
[ 525.038037] kthread+0x19a/0x1e0
[ 525.038051] ret_from_fork+0x1f/0x30
[ 525.038062]
[ 525.038074] read to 0xffff8881f145efa1 of 1 bytes by task 733 on cpu 3:
[ 525.038304] intel_rps_boost+0x67/0x1f0 [i915]
[ 525.038535] i915_request_wait+0x562/0x5d0 [i915]
[ 525.038764] i915_gem_object_wait_fence+0x81/0xa0 [i915]
[ 525.038994] i915_gem_object_wait_reservation+0x489/0x520 [i915]
[ 525.039224] i915_gem_wait_ioctl+0x167/0x2b0 [i915]
[ 525.039241] drm_ioctl_kernel+0xe4/0x120
[ 525.039255] drm_ioctl+0x297/0x4c7
[ 525.039269] ksys_ioctl+0x89/0xb0
[ 525.039282] __x64_sys_ioctl+0x42/0x60
[ 525.039296] do_syscall_64+0x6e/0x2c0
[ 525.039311] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200309113623.24208-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gt/intel_rps.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c b/drivers/gpu/drm/i915/gt/intel_rps.c
index 8794d399f5cd..c22c59ba88f2 100644
--- a/drivers/gpu/drm/i915/gt/intel_rps.c
+++ b/drivers/gpu/drm/i915/gt/intel_rps.c
@@ -644,7 +644,7 @@ void intel_rps_mark_interactive(struct intel_rps *rps, bool interactive)
{
mutex_lock(&rps->power.mutex);
if (interactive) {
- if (!rps->power.interactive++ && rps->active)
+ if (!rps->power.interactive++ && READ_ONCE(rps->active))
rps_set_power(rps, HIGH_POWER);
} else {
GEM_BUG_ON(!rps->power.interactive);
@@ -721,11 +721,14 @@ void intel_rps_unpark(struct intel_rps *rps)
* performance, jump directly to RPe as our starting frequency.
*/
mutex_lock(&rps->lock);
- rps->active = true;
+
+ WRITE_ONCE(rps->active, true);
+
freq = max(rps->cur_freq, rps->efficient_freq),
freq = clamp(freq, rps->min_freq_softlimit, rps->max_freq_softlimit);
intel_rps_set(rps, freq);
rps->last_adj = 0;
+
mutex_unlock(&rps->lock);
if (INTEL_GEN(rps_to_i915(rps)) >= 6)
@@ -745,7 +748,7 @@ void intel_rps_park(struct intel_rps *rps)
if (INTEL_GEN(i915) >= 6)
rps_disable_interrupts(rps);
- rps->active = false;
+ WRITE_ONCE(rps->active, false);
if (rps->last_freq <= rps->idle_freq)
return;
@@ -772,7 +775,7 @@ void intel_rps_boost(struct i915_request *rq)
struct intel_rps *rps = &rq->engine->gt->rps;
unsigned long flags;
- if (i915_request_signaled(rq) || !rps->active)
+ if (i915_request_signaled(rq) || !READ_ONCE(rps->active))
return;
/* Serializes with i915_request_retire() */
--
2.28.0