On Wed, May 17, 2023 at 04:54:12PM +0800, Zhen Ni wrote:
> Read syscall cannot response to sigals when data_to_read remains at 0
> and the while loop cannot break. Fix it.
>
> Signed-off-by: Zhen Ni <[email protected]>
> ---
> drivers/char/ipmi/ipmi_watchdog.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_watchdog.c
> b/drivers/char/ipmi/ipmi_watchdog.c
> index 0d4a8dcacfd4..e7eb3e140444 100644
> --- a/drivers/char/ipmi/ipmi_watchdog.c
> +++ b/drivers/char/ipmi/ipmi_watchdog.c
> @@ -807,13 +807,12 @@ static ssize_t ipmi_read(struct file *file,
> spin_unlock_irq(&ipmi_read_lock);
> schedule();
> spin_lock_irq(&ipmi_read_lock);
> + if (signal_pending(current)) {
> + rv = -ERESTARTSYS;
> + break;
> + }
This is a bug, but your fix isn't quite correct. If you do this, then
data_to_read will be set to zero on a signal, and you want to return the
ERESTARTSYS and not clear data_to_read in that case.
Instead of your fix, I have added a "!signal_pending()" to the while
loop check, which was probably my original intent.
-corey
> }
> remove_wait_queue(&read_q, &wait);
> -
> - if (signal_pending(current)) {
> - rv = -ERESTARTSYS;
> - goto out;
> - }
> }
> data_to_read = 0;
>
> --
> 2.20.1
>
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