| Message ID | 1442307754-13233-8-git-send-email-yangds.fnst@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue 15-09-15 17:02:02, Dongsheng Yang wrote: > cd_acquire() works like bd_acquire() to get cdev by an inode, > this commit is a preparation for lookup_cdev(). > > Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> Two comments below. > --- > fs/char_dev.c | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/fs/char_dev.c b/fs/char_dev.c > index ea06a3d..e818faa 100644 > --- a/fs/char_dev.c > +++ b/fs/char_dev.c > @@ -439,6 +439,41 @@ static int exact_lock(dev_t dev, void *data) > return cdev_get(p) ? 0 : -1; > } > > +struct cdev *cd_acquire(struct inode *inode) > +{ > + struct cdev *cdev; > + struct cdev *new = NULL; > + > + spin_lock(&cdev_lock); > + cdev = inode->i_cdev; > + if (!cdev) { > + struct kobject *kobj; > + int idx; Empty line here please to separate variable declarations from the code. > + spin_unlock(&cdev_lock); > + kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); > + if (!kobj) { > + cdev = NULL; > + goto out; > + } > + new = container_of(kobj, struct cdev, kobj); > + spin_lock(&cdev_lock); > + /* Check i_cdev again in case somebody beat us to it while > + we dropped the lock. */ > + cdev = inode->i_cdev; > + if (!cdev) { > + inode->i_cdev = cdev = new; > + list_add(&inode->i_devices, &cdev->list); > + } I think you need to put 'new' in case you didn't use it, don't you? > + } > + > + if (!cdev_get(cdev)) > + cdev = NULL; > + spin_unlock(&cdev_lock); > + > +out: > + return cdev; > +} > + > /** > * cdev_add() - add a char device to the system > * @p: the cdev structure for the device Honza
On 09/16/2015 04:16 PM, Jan Kara wrote: > On Tue 15-09-15 17:02:02, Dongsheng Yang wrote: >> cd_acquire() works like bd_acquire() to get cdev by an inode, >> this commit is a preparation for lookup_cdev(). >> >> Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> > > Two comments below. > >> --- >> fs/char_dev.c | 35 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 35 insertions(+) >> >> diff --git a/fs/char_dev.c b/fs/char_dev.c >> index ea06a3d..e818faa 100644 >> --- a/fs/char_dev.c >> +++ b/fs/char_dev.c >> @@ -439,6 +439,41 @@ static int exact_lock(dev_t dev, void *data) >> return cdev_get(p) ? 0 : -1; >> } >> >> +struct cdev *cd_acquire(struct inode *inode) >> +{ >> + struct cdev *cdev; >> + struct cdev *new = NULL; >> + >> + spin_lock(&cdev_lock); >> + cdev = inode->i_cdev; >> + if (!cdev) { >> + struct kobject *kobj; >> + int idx; > > Empty line here please to separate variable declarations from the code. Yes, > >> + spin_unlock(&cdev_lock); >> + kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); >> + if (!kobj) { >> + cdev = NULL; >> + goto out; >> + } >> + new = container_of(kobj, struct cdev, kobj); >> + spin_lock(&cdev_lock); >> + /* Check i_cdev again in case somebody beat us to it while >> + we dropped the lock. */ >> + cdev = inode->i_cdev; >> + if (!cdev) { >> + inode->i_cdev = cdev = new; >> + list_add(&inode->i_devices, &cdev->list); >> + } > > I think you need to put 'new' in case you didn't use it, don't you? Oh, yes, I forgot it. will update it. Thanx Yang > >> + } >> + >> + if (!cdev_get(cdev)) >> + cdev = NULL; >> + spin_unlock(&cdev_lock); >> + >> +out: >> + return cdev; >> +} >> + >> /** >> * cdev_add() - add a char device to the system >> * @p: the cdev structure for the device > > Honza > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/char_dev.c b/fs/char_dev.c index ea06a3d..e818faa 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -439,6 +439,41 @@ static int exact_lock(dev_t dev, void *data) return cdev_get(p) ? 0 : -1; } +struct cdev *cd_acquire(struct inode *inode) +{ + struct cdev *cdev; + struct cdev *new = NULL; + + spin_lock(&cdev_lock); + cdev = inode->i_cdev; + if (!cdev) { + struct kobject *kobj; + int idx; + spin_unlock(&cdev_lock); + kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); + if (!kobj) { + cdev = NULL; + goto out; + } + new = container_of(kobj, struct cdev, kobj); + spin_lock(&cdev_lock); + /* Check i_cdev again in case somebody beat us to it while + we dropped the lock. */ + cdev = inode->i_cdev; + if (!cdev) { + inode->i_cdev = cdev = new; + list_add(&inode->i_devices, &cdev->list); + } + } + + if (!cdev_get(cdev)) + cdev = NULL; + spin_unlock(&cdev_lock); + +out: + return cdev; +} + /** * cdev_add() - add a char device to the system * @p: the cdev structure for the device
cd_acquire() works like bd_acquire() to get cdev by an inode, this commit is a preparation for lookup_cdev(). Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> --- fs/char_dev.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+)