serial: sh-sci: Fix locking in sci_submit_rx()

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[ Upstream commit dd1f2250da ]

Some callers of sci_submit_rx() hold the port spinlock, others don't.
During fallback to PIO, the driver needs to obtain the port spinlock.
If the lock was already held, spinlock recursion is detected, causing a
deadlock: BUG: spinlock recursion on CPU#0.

Fix this by adding a flag parameter to sci_submit_rx() for the caller to
indicate the port spinlock is already held, so spinlock recursion can be
avoided.

Move the spin_lock_irqsave() up, so all DMA disable steps are protected,
which is safe as the recently introduced dmaengine_terminate_async() can
be called in atomic context.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

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Geert Uytterhoeven 2018-12-13 19:44:41 +01:00 • committed by Greg Kroah-Hartman

parent 7e018cddb7

commit 556822da8d

1 changed files with 9 additions and 7 deletions

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drivers/tty/serial/sh-sci.c

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