| Message ID | 20200309172238.GJ267906@xps-13 |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v2] ptp: free ptp clock properly | expand |
On Mon, Mar 09, 2020 at 06:22:38PM +0100, Andrea Righi wrote: > There is a bug in ptp_clock_unregister() where pps_unregister_source() > can free up resources needed by posix_clock_unregister() to properly > destroy a related sysfs device. This text is inadequate. It does not identify the problem. What resources? Which related device? > Fix this by calling pps_unregister_source() in ptp_clock_release(). This statement is redundant, as we can see that from the patch itself. Instead of saying WHAT the patch does, please explain WHY that fixes the issue (which, as I said, you still need to identify). Thanks, Richard
Hello, Andrea, Colin, all, This fix is really not needed, as its creation is based on the assumption that the Ubuntu kernel 5.3.0-40-generic has the upstream commit 75718584cb3c, which is the real fix to this crash. > > > I would guess that a kernel in question (5.3.0-40-generic) has the commit > > > a33121e5487b but does not have the commit 75718584cb3c, which should be > > > exactly fixing a docking station disconnect crash. Could you please, > > > check this? > > > > Unfortunately the kernel in question already has 75718584cb3c: > > https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic/commit/?h=hwe&id=c71b774732f997ef38ed7bd62e73891a01f2bbfe Apologies, but the assumption above is not correct, 5.3.0-40-generic does not have 75718584cb3c. If it had 75718584cb3c it would be a fix and the ptp-related crash (described in https://bugs.launchpad.net/bugs/1864754) would not happen. This way https://lists.ubuntu.com/archives/kernel-team/2020-March/108562.html fix is not really needed. Best regards, Vladis Dronov | Red Hat, Inc. | The Core Kernel | Senior Software Engineer ----- Original Message ----- > From: "Andrea Righi" <andrea.righi@canonical.com> > To: "Richard Cochran" <richardcochran@gmail.com>, "Vladis Dronov" <vdronov@redhat.com> > Cc: "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org, linux-kernel@vger.kernel.org > Sent: Monday, March 9, 2020 6:22:38 PM > Subject: [PATCH v2] ptp: free ptp clock properly > > There is a bug in ptp_clock_unregister() where pps_unregister_source() > can free up resources needed by posix_clock_unregister() to properly > destroy a related sysfs device. > > Fix this by calling pps_unregister_source() in ptp_clock_release(). > > See also: > commit 75718584cb3c ("ptp: free ptp device pin descriptors properly"). > > BugLink: https://bugs.launchpad.net/bugs/1864754 > Fixes: a33121e5487b ("ptp: fix the race between the release of ptp_clock and > cdev") > Tested-by: Piotr Morgwai Kotarbiński <foss@morgwai.pl> > Signed-off-by: Andrea Righi <andrea.righi@canonical.com> > --- > > v2: move pps_unregister_source() to ptp_clock_release(), instead of > posix_clock_unregister(), that would just introduce a resource leak > > drivers/ptp/ptp_clock.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c > index ac1f2bf9e888..468286ef61ad 100644 > --- a/drivers/ptp/ptp_clock.c > +++ b/drivers/ptp/ptp_clock.c > @@ -170,6 +170,9 @@ static void ptp_clock_release(struct device *dev) > { > struct ptp_clock *ptp = container_of(dev, struct ptp_clock, dev); > > + /* Release the clock's resources. */ > + if (ptp->pps_source) > + pps_unregister_source(ptp->pps_source); > ptp_cleanup_pin_groups(ptp); > mutex_destroy(&ptp->tsevq_mux); > mutex_destroy(&ptp->pincfg_mux); > @@ -298,11 +301,6 @@ int ptp_clock_unregister(struct ptp_clock *ptp) > kthread_cancel_delayed_work_sync(&ptp->aux_work); > kthread_destroy_worker(ptp->kworker); > } > - > - /* Release the clock's resources. */ > - if (ptp->pps_source) > - pps_unregister_source(ptp->pps_source); > - > posix_clock_unregister(&ptp->clock); > > return 0; > -- > 2.25.0
On Fri, Apr 03, 2020 at 09:34:14AM -0400, Vladis Dronov wrote: > Hello, Andrea, Colin, all, > > This fix is really not needed, as its creation is based on the assumption > that the Ubuntu kernel 5.3.0-40-generic has the upstream commit 75718584cb3c, > which is the real fix to this crash. > > > > > I would guess that a kernel in question (5.3.0-40-generic) has the commit > > > > a33121e5487b but does not have the commit 75718584cb3c, which should be > > > > exactly fixing a docking station disconnect crash. Could you please, > > > > check this? > > > > > > Unfortunately the kernel in question already has 75718584cb3c: > > > https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic/commit/?h=hwe&id=c71b774732f997ef38ed7bd62e73891a01f2bbfe > > Apologies, but the assumption above is not correct, 5.3.0-40-generic does > not have 75718584cb3c. If it had 75718584cb3c it would be a fix and the ptp-related > crash (described in https://bugs.launchpad.net/bugs/1864754) would not happen. > > This way https://lists.ubuntu.com/archives/kernel-team/2020-March/108562.html fix > is not really needed. Hi Vladis, for the records, I repeated the tests with a lot of help from the bug reporter (Morgwai, added in cc), this time making sure we were using the same kernels. I confirm that my fix is not really needed as you correctly pointed out. Thanks for looking into this and sorry for the noise! :) -Andrea
Hello, ----- Original Message ----- > From: "Andrea Righi" <andrea.righi@canonical.com> > To: "Vladis Dronov" <vdronov@redhat.com> > Cc: "Piotr Morgwai Kotarbiński" <morgwai@morgwai.pl>, "Colin Ian King" <colin.king@canonical.com>, "Richard Cochran" > <richardcochran@gmail.com>, "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org, > linux-kernel@vger.kernel.org > Sent: Tuesday, April 7, 2020 11:34:22 AM > Subject: Re: [PATCH v2] ptp: free ptp clock properly > > On Fri, Apr 03, 2020 at 09:34:14AM -0400, Vladis Dronov wrote: > > Hello, Andrea, Colin, all, > > > > This fix is really not needed, as its creation is based on the assumption > > that the Ubuntu kernel 5.3.0-40-generic has the upstream commit > > 75718584cb3c, > > which is the real fix to this crash. > > > > > > > I would guess that a kernel in question (5.3.0-40-generic) has the > > > > > commit > > > > > a33121e5487b but does not have the commit 75718584cb3c, which should > > > > > be > > > > > exactly fixing a docking station disconnect crash. Could you please, > > > > > check this? > > > > > > > > Unfortunately the kernel in question already has 75718584cb3c: > > > > https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic/commit/?h=hwe&id=c71b774732f997ef38ed7bd62e73891a01f2bbfe > > > > Apologies, but the assumption above is not correct, 5.3.0-40-generic does > > not have 75718584cb3c. If it had 75718584cb3c it would be a fix and the > > ptp-related > > crash (described in https://bugs.launchpad.net/bugs/1864754) would not > > happen. > > > > This way > > https://lists.ubuntu.com/archives/kernel-team/2020-March/108562.html fix > > is not really needed. > > Hi Vladis, > > for the records, I repeated the tests with a lot of help from the bug > reporter (Morgwai, added in cc), this time making sure we were using the > same kernels. > > I confirm that my fix is not really needed as you correctly pointed out. > Thanks for looking into this and sorry for the noise! :) Hei, great! Thank you for updating. I'm happy this situation has resolved properly! > > -Andrea > Best regards, Vladis Dronov | Red Hat, Inc. | The Core Kernel | Senior Software Engineer
diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c index ac1f2bf9e888..468286ef61ad 100644 --- a/drivers/ptp/ptp_clock.c +++ b/drivers/ptp/ptp_clock.c @@ -170,6 +170,9 @@ static void ptp_clock_release(struct device *dev) { struct ptp_clock *ptp = container_of(dev, struct ptp_clock, dev); + /* Release the clock's resources. */ + if (ptp->pps_source) + pps_unregister_source(ptp->pps_source); ptp_cleanup_pin_groups(ptp); mutex_destroy(&ptp->tsevq_mux); mutex_destroy(&ptp->pincfg_mux); @@ -298,11 +301,6 @@ int ptp_clock_unregister(struct ptp_clock *ptp) kthread_cancel_delayed_work_sync(&ptp->aux_work); kthread_destroy_worker(ptp->kworker); } - - /* Release the clock's resources. */ - if (ptp->pps_source) - pps_unregister_source(ptp->pps_source); - posix_clock_unregister(&ptp->clock); return 0;
There is a bug in ptp_clock_unregister() where pps_unregister_source() can free up resources needed by posix_clock_unregister() to properly destroy a related sysfs device. Fix this by calling pps_unregister_source() in ptp_clock_release(). See also: commit 75718584cb3c ("ptp: free ptp device pin descriptors properly"). BugLink: https://bugs.launchpad.net/bugs/1864754 Fixes: a33121e5487b ("ptp: fix the race between the release of ptp_clock and cdev") Tested-by: Piotr Morgwai Kotarbiński <foss@morgwai.pl> Signed-off-by: Andrea Righi <andrea.righi@canonical.com> --- v2: move pps_unregister_source() to ptp_clock_release(), instead of posix_clock_unregister(), that would just introduce a resource leak drivers/ptp/ptp_clock.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)