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uio: uio_dmem_genirq: Fix deadlock between irq config and handling

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[ Upstream commit 118b918018175d9fcd8db667f905012e986cc2c9 ]

This fixes a concurrency issue addressed in commit 34cb275283 ("UIO: Fix
concurrency issue"):

  "In a SMP case there was a race condition issue between
  Uio_pdrv_genirq_irqcontrol() running on one CPU and irq handler on
  another CPU. Fix it by spin_locking shared resources access inside irq
  handler."

The implementation of "uio_dmem_genirq" was based on "uio_pdrv_genirq" and
it is used in a similar manner to the "uio_pdrv_genirq" driver with respect
to interrupt configuration and handling. At the time "uio_dmem_genirq" was
merged, both had the same implementation of the 'uio_info' handlers
irqcontrol() and handler(), thus, both had the same concurrency issue
mentioned by the above commit. However, the above patch was only applied to
the "uio_pdrv_genirq" driver.

Split out from commit 34cb275283 ("UIO: Fix concurrency issue").

Fixes: 0a0c3b5a24 ("Add new uio device for dynamic memory allocation")
Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com>
Link: https://lore.kernel.org/r/20220930224100.816175-3-rafaelmendsr@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Rafael Mendonca 2022-09-30 19:40:58 -03:00 committed by Greg Kroah-Hartman
parent eca77a25a7
commit 12d20ba3ce
1 changed files with 4 additions and 1 deletions
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5
drivers/uio/uio_dmem_genirq.c
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@ -110,8 +110,10 @@ static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
* remember the state so we can allow user space to enable it later.
*/
spin_lock(&priv->lock);
if (!test_and_set_bit(0, &priv->flags))
disable_irq_nosync(irq);
spin_unlock(&priv->lock);
return IRQ_HANDLED;
}
@ -125,7 +127,8 @@ static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
* in the interrupt controller, but keep track of the
* state to prevent per-irq depth damage.
*
* Serialize this operation to support multiple tasks.
* Serialize this operation to support multiple tasks and concurrency
* with irq handler on SMP systems.
*/
spin_lock_irqsave(&priv->lock, flags);