Edward!
On Sun, Nov 05, 2023 at 10:12:08AM +0800, Edward Adam Davis wrote:
> There is no lock protection when writing ptp->tsevqs in ptp_open() and
> ptp_release(), which can cause data corruption, use spin 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.
Change to: "it should be deleted altogether"
> Reported-and-tested-by: [email protected]
> Fixes: 8f5de6fb2453 ("ptp: support multiple timestamp event readers")
> Signed-off-by: Edward Adam Davis <[email protected]>
> ---
> drivers/ptp/ptp_chardev.c | 11 +++++++----
> drivers/ptp/ptp_clock.c | 1 +
> drivers/ptp/ptp_private.h | 1 +
> 3 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
> index 282cd7d24077..31594f40a21e 100644
> --- a/drivers/ptp/ptp_chardev.c
> +++ b/drivers/ptp/ptp_chardev.c
> @@ -108,6 +108,7 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
> container_of(pccontext->clk, struct ptp_clock, clock);
> struct timestamp_event_queue *queue;
> char debugfsname[32];
> + unsigned long flags;
>
> queue = kzalloc(sizeof(*queue), GFP_KERNEL);
> if (!queue)
> @@ -119,8 +120,10 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
> }
> bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
> spin_lock_init(&queue->lock);
> + spin_lock_irqsave(&ptp->tsevqs_lock, flags);
> list_add_tail(&queue->qlist, &ptp->tsevqs);
> pccontext->private_clkdata = queue;
Move this assignment outside of locked region, i.e. after spin_unlock_irqrestore().
> + spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
>
> /* Debugfs contents */
> sprintf(debugfsname, "0x%p", queue);
> @@ -139,13 +142,15 @@ int ptp_release(struct posix_clock_context *pccontext)
> {
> struct timestamp_event_queue *queue = pccontext->private_clkdata;
> unsigned long flags;
> + struct ptp_clock *ptp =
> + container_of(pccontext->clk, struct ptp_clock, clock);
>
> if (queue) {
Please remove this test. Since you removed ptp_release() from
ptp_read(), the queue cannot be NULL.
> debugfs_remove(queue->debugfs_instance);
> + spin_lock_irqsave(&ptp->tsevqs_lock, flags);
> pccontext->private_clkdata = NULL;
Move this assignment outside of locked region.
> - spin_lock_irqsave(&queue->lock, flags);
> list_del(&queue->qlist);
> - spin_unlock_irqrestore(&queue->lock, flags);
> + spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
> bitmap_free(queue->mask);
> kfree(queue);
> }
> @@ -585,7 +590,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
> free_event:
> kfree(event);
> exit:
> - if (result < 0)
> - ptp_release(pccontext);
This is good, but please put it into a separate patch, along with the
removal of the bogus "if (queue)" test in ptp_release().
> return result;
> }
> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index 3d1b0a97301c..ea82648ad557 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -247,6 +247,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> if (!queue)
> goto no_memory_queue;
> list_add_tail(&queue->qlist, &ptp->tsevqs);
> + spin_lock_init(&ptp->tsevqs_lock);
> queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
> if (!queue->mask)
> goto no_memory_bitmap;
> diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
> index 52f87e394aa6..63af246f17eb 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 */
> + spinlock_t tsevqs_lock; /* one process at a time writing the timestamp fifo list*/
Please change this comment to "protects tsevqs from concurrent access"
> struct mutex pincfg_mux; /* protect concurrent info->pin_config access */
> wait_queue_head_t tsev_wq;
> int defunct; /* tells readers to go away when clock is being removed */
> --
> 2.25.1
>
Since v6.6 now contains the original commit, please change subject to [net].
Thanks,
Richard
On Sun, Nov 05, 2023 at 05:36:41AM -0800, Richard Cochran wrote:
> > @@ -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 */
> > + spinlock_t tsevqs_lock; /* one process at a time writing the timestamp fifo list*/
>
> Please change this comment to "protects tsevqs from concurrent access"
And please don't forget to take the spin lock around
list_for_each_entry() in ptp_clock_event().
Thanks,
Richard