linux-kernel - [PATCH] drm/i915: Use tasklet_unlock_spin_wait() in __tasklet_disable_sync

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Message-ID: <20210323092221.awq7g5b2muzypjw3@flow>
Date:   Tue, 23 Mar 2021 10:22:21 +0100
From:   Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     kernel test robot <oliver.sang@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        lkp@...ts.01.org, lkp@...el.com,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>
Subject: [PATCH] drm/i915: Use tasklet_unlock_spin_wait() in
 __tasklet_disable_sync_once()

The i915 driver has its own tasklet interface which was overseen in the
tasklet rework. __tasklet_disable_sync_once() is a wrapper around
tasklet_unlock_wait(). tasklet_unlock_wait() might sleep, but the i915
wrappers invoke it from non-preemtible contexts with bottom halves disabled.

Use tasklet_unlock_spin_wait() instead which can be invoked from
non-preemptible contexts.

Fixes: da044747401fc ("tasklets: Replace spin wait in tasklet_unlock_wait()")
Reported-by: kernel test robot <oliver.sang@...el.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 drivers/gpu/drm/i915/i915_gem.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index e622aee6e4be9..440c35f1abc9e 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -105,7 +105,7 @@ static inline bool tasklet_is_locked(const struct tasklet_struct *t)
 static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
 {
 	if (!atomic_fetch_inc(&t->count))
-		tasklet_unlock_wait(t);
+		tasklet_unlock_spin_wait(t);
 }
 
 static inline bool __tasklet_is_enabled(const struct tasklet_struct *t)
-- 
2.31.0