| Message ID | 154949781334.10620.18347323437724979128.stgit@noble.brown (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | lustre: Assorted cleanups for obdclass | expand |
On Feb 6, 2019, at 17:03, NeilBrown <neilb@suse.com> wrote: > > If try_module_get() fails, the open must fail. > > In practice this should be impossible, but it is > best to make the code look right. > > Signed-off-by: NeilBrown <neilb@suse.com> Reviewed-by: Andreas Dilger <adilger@whamcloud.com> Cheers, Andreas --- Andreas Dilger Principal Lustre Architect Whamcloud
> If try_module_get() fails, the open must fail. > > In practice this should be impossible, but it is > best to make the code look right. I remembar having discussion with Greg about this approach in libcfs. He though it was racey to do this in general. The discussion was a while ago so I need to dig up the thread. In the end we remove the whole module handling in the xxx_open() and such. > Signed-off-by: NeilBrown <neilb@suse.com> > --- > drivers/staging/lustre/lustre/obdclass/class_obd.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/staging/lustre/lustre/obdclass/class_obd.c b/drivers/staging/lustre/lustre/obdclass/class_obd.c > index 48d1dabafa65..982d47b6f50e 100644 > --- a/drivers/staging/lustre/lustre/obdclass/class_obd.c > +++ b/drivers/staging/lustre/lustre/obdclass/class_obd.c > @@ -548,8 +548,7 @@ int class_handle_ioctl(unsigned int cmd, unsigned long arg) > /* opening /dev/obd */ > static int obd_class_open(struct inode *inode, struct file *file) > { > - try_module_get(THIS_MODULE); > - return 0; > + return try_module_get(THIS_MODULE) ? 0 : -ENODEV; > } > > /* closing /dev/obd */ > > >
On Mon, Feb 11 2019, James Simmons wrote: >> If try_module_get() fails, the open must fail. >> >> In practice this should be impossible, but it is >> best to make the code look right. > > I remembar having discussion with Greg about this approach in libcfs. > He though it was racey to do this in general. The discussion was a > while ago so I need to dig up the thread. In the end we remove the > whole module handling in the xxx_open() and such. Yes, you are right. This should just be removed. This is a chardev, and the .owner of a chardev will always have a reference held while the device is open - cdev_get/cdev_put ensure that. We can just get rid of the obd_class_open and obd_class_release. I'll drop this patch and replace it. Thanks, NeilBrown > >> Signed-off-by: NeilBrown <neilb@suse.com> >> --- >> drivers/staging/lustre/lustre/obdclass/class_obd.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/staging/lustre/lustre/obdclass/class_obd.c b/drivers/staging/lustre/lustre/obdclass/class_obd.c >> index 48d1dabafa65..982d47b6f50e 100644 >> --- a/drivers/staging/lustre/lustre/obdclass/class_obd.c >> +++ b/drivers/staging/lustre/lustre/obdclass/class_obd.c >> @@ -548,8 +548,7 @@ int class_handle_ioctl(unsigned int cmd, unsigned long arg) >> /* opening /dev/obd */ >> static int obd_class_open(struct inode *inode, struct file *file) >> { >> - try_module_get(THIS_MODULE); >> - return 0; >> + return try_module_get(THIS_MODULE) ? 0 : -ENODEV; >> } >> >> /* closing /dev/obd */ >> >> >>
diff --git a/drivers/staging/lustre/lustre/obdclass/class_obd.c b/drivers/staging/lustre/lustre/obdclass/class_obd.c index 48d1dabafa65..982d47b6f50e 100644 --- a/drivers/staging/lustre/lustre/obdclass/class_obd.c +++ b/drivers/staging/lustre/lustre/obdclass/class_obd.c @@ -548,8 +548,7 @@ int class_handle_ioctl(unsigned int cmd, unsigned long arg) /* opening /dev/obd */ static int obd_class_open(struct inode *inode, struct file *file) { - try_module_get(THIS_MODULE); - return 0; + return try_module_get(THIS_MODULE) ? 0 : -ENODEV; } /* closing /dev/obd */
If try_module_get() fails, the open must fail. In practice this should be impossible, but it is best to make the code look right. Signed-off-by: NeilBrown <neilb@suse.com> --- drivers/staging/lustre/lustre/obdclass/class_obd.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)