From: Rafael Mendonca rafaelmendsr@gmail.com
[ Upstream commit 118b918018175d9fcd8db667f905012e986cc2c9 ]
This fixes a concurrency issue addressed in commit 34cb27528398 ("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 34cb27528398 ("UIO: Fix concurrency issue").
Fixes: 0a0c3b5a24bd ("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 --- drivers/uio/uio_dmem_genirq.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/uio/uio_dmem_genirq.c b/drivers/uio/uio_dmem_genirq.c index 796946bab508..92751737bbea 100644 --- a/drivers/uio/uio_dmem_genirq.c +++ b/drivers/uio/uio_dmem_genirq.c @@ -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);