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[5/7] Input: libps2 - fix aborting PS/2 commands

Message ID 20230511185252.386941-6-dmitry.torokhov@gmail.com (mailing list archive)
State Mainlined
Commit 7d674f9150c361e5b992551b46516d41eede3722
Headers show
Series libps2: be more tolerant when processing commands | expand

Commit Message

Dmitry Torokhov May 11, 2023, 6:52 p.m. UTC 
When aborting PS/2 command the kernel should [re]set all flags before
waking up waiters, otherwise waiting thread may read obsolete values
of flags.

Reported-by: Raul Rangel <rrangel@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/serio/libps2.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

Comments

Raul Rangel May 18, 2023, 5:22 p.m. UTC | #1 
On Thu, May 11, 2023 at 11:52:45AM -0700, Dmitry Torokhov wrote:
> When aborting PS/2 command the kernel should [re]set all flags before
> waking up waiters, otherwise waiting thread may read obsolete values
> of flags.
> 
> Reported-by: Raul Rangel <rrangel@chromium.org>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>  drivers/input/serio/libps2.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
> index 14b70a78875d..09eb605364bb 100644
> --- a/drivers/input/serio/libps2.c
> +++ b/drivers/input/serio/libps2.c
> @@ -478,15 +478,22 @@ bool ps2_handle_response(struct ps2dev *ps2dev, u8 data)
>  }
>  EXPORT_SYMBOL(ps2_handle_response);
>  
> +/*
> + * Clears state of PS/2 device after communication error by resetting majority
> + * of flags and waking up waiters, if any.
> + */
>  void ps2_cmd_aborted(struct ps2dev *ps2dev)
>  {
> -	if (ps2dev->flags & PS2_FLAG_ACK)
> +	unsigned long old_flags = ps2dev->flags;
> +
> +	/* reset all flags except last nak */
> +	ps2dev->flags &= PS2_FLAG_NAK;
> +
> +	if (old_flags & PS2_FLAG_ACK)
>  		ps2dev->nak = 1;
>  
> -	if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
> +	if (old_flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
>  		wake_up(&ps2dev->wait);
>  
> -	/* reset all flags except last nack */
> -	ps2dev->flags &= PS2_FLAG_NAK;
>  }
>  EXPORT_SYMBOL(ps2_cmd_aborted);
Reviewed-by: Raul E Rangel <rrangel@chromium.org>
diff mbox series

Patch

diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 14b70a78875d..09eb605364bb 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -478,15 +478,22 @@  bool ps2_handle_response(struct ps2dev *ps2dev, u8 data)
 }
 EXPORT_SYMBOL(ps2_handle_response);
 
+/*
+ * Clears state of PS/2 device after communication error by resetting majority
+ * of flags and waking up waiters, if any.
+ */
 void ps2_cmd_aborted(struct ps2dev *ps2dev)
 {
-	if (ps2dev->flags & PS2_FLAG_ACK)
+	unsigned long old_flags = ps2dev->flags;
+
+	/* reset all flags except last nak */
+	ps2dev->flags &= PS2_FLAG_NAK;
+
+	if (old_flags & PS2_FLAG_ACK)
 		ps2dev->nak = 1;
 
-	if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
+	if (old_flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
 		wake_up(&ps2dev->wait);
 
-	/* reset all flags except last nack */
-	ps2dev->flags &= PS2_FLAG_NAK;
 }
 EXPORT_SYMBOL(ps2_cmd_aborted);