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drm/v3d: Appease lockdep while updating GPU stats
[ Upstream commit 06c3c40 ] Lockdep thinks our seqcount_t usage is unsafe because the update path can be both from irq and worker context: [ ] ================================ [ ] WARNING: inconsistent lock state [ ] 6.10.3-v8-16k-numa torvalds#159 Tainted: G WC [ ] -------------------------------- [ ] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. [ ] swapper/0/0 [HC1[1]:SC0[0]:HE0:SE1] takes: [ ] ffff80003d7c08d0 (&v3d_priv->stats[i].lock){?.+.}-{0:0}, at: v3d_irq+0xc8/0x660 [v3d] [ ] {HARDIRQ-ON-W} state was registered at: [ ] lock_acquire+0x1f8/0x328 [ ] v3d_job_start_stats.isra.0+0xd8/0x218 [v3d] [ ] v3d_bin_job_run+0x23c/0x388 [v3d] [ ] drm_sched_run_job_work+0x520/0x6d0 [gpu_sched] [ ] process_one_work+0x62c/0xb48 [ ] worker_thread+0x468/0x5b0 [ ] kthread+0x1c4/0x1e0 [ ] ret_from_fork+0x10/0x20 [ ] irq event stamp: 337094 [ ] hardirqs last enabled at (337093): [<ffffc0008144ce7c>] default_idle_call+0x11c/0x140 [ ] hardirqs last disabled at (337094): [<ffffc0008144a354>] el1_interrupt+0x24/0x58 [ ] softirqs last enabled at (337082): [<ffffc00080061d90>] handle_softirqs+0x4e0/0x538 [ ] softirqs last disabled at (337073): [<ffffc00080010364>] __do_softirq+0x1c/0x28 [ ] other info that might help us debug this: [ ] Possible unsafe locking scenario: [ ] CPU0 [ ] ---- [ ] lock(&v3d_priv->stats[i].lock); [ ] <Interrupt> [ ] lock(&v3d_priv->stats[i].lock); [ ] *** DEADLOCK *** [ ] no locks held by swapper/0/0. [ ] stack backtrace: [ ] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G WC 6.10.3-v8-16k-numa torvalds#159 [ ] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT) [ ] Call trace: [ ] dump_backtrace+0x170/0x1b8 [ ] show_stack+0x20/0x38 [ ] dump_stack_lvl+0xb4/0xd0 [ ] dump_stack+0x18/0x28 [ ] print_usage_bug+0x3cc/0x3f0 [ ] mark_lock+0x4d0/0x968 [ ] __lock_acquire+0x784/0x18c8 [ ] lock_acquire+0x1f8/0x328 [ ] v3d_job_update_stats+0xec/0x2e0 [v3d] [ ] v3d_irq+0xc8/0x660 [v3d] [ ] __handle_irq_event_percpu+0x1f8/0x488 [ ] handle_irq_event+0x88/0x128 [ ] handle_fasteoi_irq+0x298/0x408 [ ] generic_handle_domain_irq+0x50/0x78 But it is a false positive because all the queue-stats pairs have their own lock and jobs are also one at a time. Nevertheless we can appease lockdep by disabling local interrupts to make it see lock usage is consistent. Cc: Maíra Canal <mcanal@igalia.com> Fixes: 6abe93b ("drm/v3d: Fix race-condition between sysfs/fdinfo and interrupt handler") Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com> Signed-off-by: Maíra Canal <mcanal@igalia.com> Link: https://patchwork.freedesktop.org/patch/msgid/20240813102505.80512-2-tursulin@igalia.com Signed-off-by: Sasha Levin <sashal@kernel.org>
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