On Fri, Nov 03, 2023 at 09:15:03PM +0800, Edward Adam Davis wrote:
> There is no lock protection when writing ptp->tsevqs in ptp_open(),
> ptp_release(), which can cause data corruption, use mutex lock to avoid this
> issue.
>
> Moreover, ptp_release() should not be used to release the queue in ptp_read(),
> and it should be deleted together.
Oh, now I see what you are fixing...
> @@ -138,14 +143,19 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
> int ptp_release(struct posix_clock_context *pccontext)
> {
> struct timestamp_event_queue *queue = pccontext->private_clkdata;
> + struct ptp_clock *ptp =
> + container_of(pccontext->clk, struct ptp_clock, clock);
> unsigned long flags;
>
> if (queue) {
> + if (mutex_lock_interruptible(&ptp->tsevq_mux))
> + return -ERESTARTSYS;
I don't think it is a good idea to return ERESTARTSYS on signal here.
The release method needs to succeed.
> debugfs_remove(queue->debugfs_instance);
> pccontext->private_clkdata = NULL;
> spin_lock_irqsave(&queue->lock, flags);
This spin lock is wrong. The spin lock protects the queue, not the
list of queues.
The spin lock/unlock needs to be replaced with mutex lock/unlock.
> list_del(&queue->qlist);
> spin_unlock_irqrestore(&queue->lock, flags);
> + mutex_unlock(&ptp->tsevq_mux);
> bitmap_free(queue->mask);
> kfree(queue);
> }
> diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
> index 52f87e394aa6..1525bd2059ba 100644
> --- a/drivers/ptp/ptp_private.h
> +++ b/drivers/ptp/ptp_private.h
> @@ -44,6 +44,7 @@ struct ptp_clock {
> struct pps_device *pps_source;
> long dialed_frequency; /* remembers the frequency adjustment */
> struct list_head tsevqs; /* timestamp fifo list */
> + struct mutex tsevq_mux; /* one process at a time reading the fifo */
This comment is very misleading. The mutex does not protect the
fifo. It protects 'tsevqs' from concurrent access.
Thanks,
Richard