On Wed, 5 June 2013 17:18:33 +0800, vaughan wrote:
>
> Check and set sdp->exclude should be atomic when set in sg_open().
The patch is line-wrapped. More importantly, it doesn't seem to do
what your description indicates it should do. And lastly, does this
fix a bug, possibly even one you have a testcase for, or was it found
by code inspection?
> Signed-off-by: Vaughan Cao <vaughan.cao@xxxxxxxxxx>
> ---
> drivers/scsi/sg.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
> index 25b5455..0ede08f 100644
> --- a/drivers/scsi/sg.c
> +++ b/drivers/scsi/sg.c
> @@ -245,6 +245,21 @@ static int set_exclude(Sg_device *sdp, char val)
> return val;
> }
>
> +/* Check if we can set exclude and then set, return 1 if success */
> +static int try_set_exclude(Sg_device *sdp)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&sg_open_exclusive_lock, flags);
> + if (sdp->exclude) {
> + spin_unlock_irqrestore(&sg_open_exclusive_lock, flags);
> + return 0;
> + }
> + sdp->exclude = 1;
> + spin_unlock_irqrestore(&sg_open_exclusive_lock, flags);
> + return 1;
> +}
> +
> static int sfds_list_empty(Sg_device *sdp)
> {
> unsigned long flags;
> @@ -303,7 +318,7 @@ sg_open(struct inode *inode, struct file *filp)
> goto error_out;
> }
> res = wait_event_interruptible(sdp->o_excl_wait,
> - ((!sfds_list_empty(sdp) || get_exclude(sdp))
> ? 0 : set_exclude(sdp, 1)));
> + ((!sfds_list_empty(sdp) || get_exclude(sdp)) ? 0 :
> try_set_exclude(sdp)));
> if (res) {
> retval = res; /* -ERESTARTSYS because signal hit process */
> goto error_out;
> --
> 1.7.11.7
>
Jörn
--
Fantasy is more important than knowledge. Knowledge is limited,
while fantasy embraces the whole world.
-- Albert Einstein
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