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| author | Rafael Mendonca <rafaelmendsr@gmail.com> | 2022-09-30 19:40:58 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-10 18:54:29 +0100 |
| commit | 118b918018175d9fcd8db667f905012e986cc2c9 (patch) | |
| tree | dec5fe0c7be7fd898823bf78a804311604fba03c /drivers/uio | |
| parent | 9de255c461d1b3f0242b3ad1450c3323a3e00b34 (diff) | |
| download | lwn-118b918018175d9fcd8db667f905012e986cc2c9.tar.gz lwn-118b918018175d9fcd8db667f905012e986cc2c9.zip | |
uio: uio_dmem_genirq: Fix deadlock between irq config and handling
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>
Diffstat (limited to 'drivers/uio')
| -rw-r--r-- | drivers/uio/uio_dmem_genirq.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/uio/uio_dmem_genirq.c b/drivers/uio/uio_dmem_genirq.c index cb283ee36eaa..792c3e9c9ce5 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); |