| Message ID | 1617710898-49064-1-git-send-email-huangguobin4@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [-next] NFSD: Use DEFINE_SPINLOCK() for spinlock | expand |
> On Apr 6, 2021, at 8:08 AM, Huang Guobin <huangguobin4@huawei.com> wrote: > > From: Guobin Huang <huangguobin4@huawei.com> > > spinlock can be initialized automatically with DEFINE_SPINLOCK() > rather than explicitly calling spin_lock_init(). > > Reported-by: Hulk Robot <hulkci@huawei.com> > Signed-off-by: Guobin Huang <huangguobin4@huawei.com> This same patch was sent last July, without the Reported-by: https://lore.kernel.org/linux-nfs/1617710898-49064-1-git-send-email-huangguobin4@huawei.com/T/#u If I'm reading the code correctly, it appears that set_max_drc() can be called more than once by user space API functions via nfsd_create_serv(). It seems to me we want to guarantee that nfsd_drc_lock is initialized exactly once, and using DEFINE_SPINLOCK() would do just that. Likewise, re-initializing nfsd_drc_mem_used is probably not good to do either, but clobbering a spinlock like that might lead to a crash. Bruce, any further thoughts? > --- > fs/nfsd/nfssvc.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c > index b2eef4112bc2..82ba034fa579 100644 > --- a/fs/nfsd/nfssvc.c > +++ b/fs/nfsd/nfssvc.c > @@ -84,7 +84,7 @@ DEFINE_MUTEX(nfsd_mutex); > * version 4.1 DRC caches. > * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage. > */ > -spinlock_t nfsd_drc_lock; > +DEFINE_SPINLOCK(nfsd_drc_lock); > unsigned long nfsd_drc_max_mem; > unsigned long nfsd_drc_mem_used; > > @@ -563,7 +563,6 @@ static void set_max_drc(void) > nfsd_drc_max_mem = (nr_free_buffer_pages() > >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE; > nfsd_drc_mem_used = 0; > - spin_lock_init(&nfsd_drc_lock); > dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem); > } > > -- Chuck Lever
On Tue, Apr 06, 2021 at 03:46:34PM +0000, Chuck Lever III wrote: > > > > On Apr 6, 2021, at 8:08 AM, Huang Guobin <huangguobin4@huawei.com> wrote: > > > > From: Guobin Huang <huangguobin4@huawei.com> > > > > spinlock can be initialized automatically with DEFINE_SPINLOCK() > > rather than explicitly calling spin_lock_init(). > > > > Reported-by: Hulk Robot <hulkci@huawei.com> > > Signed-off-by: Guobin Huang <huangguobin4@huawei.com> > > This same patch was sent last July, without the Reported-by: > > https://lore.kernel.org/linux-nfs/1617710898-49064-1-git-send-email-huangguobin4@huawei.com/T/#u > > If I'm reading the code correctly, it appears that set_max_drc() > can be called more than once by user space API functions via > nfsd_create_serv(). > > It seems to me we want to guarantee that nfsd_drc_lock is > initialized exactly once, and using DEFINE_SPINLOCK() would > do just that. > > Likewise, re-initializing nfsd_drc_mem_used is probably not good > to do either, but clobbering a spinlock like that might lead to > a crash. > > Bruce, any further thoughts? The other nfsd_drc_lock users run in nfsd threads, which shouldn't be running yet at the point we call set_max_drc. Reinitializing the lock each time is pretty weird, though, ACK to the patch even if it's just cleanup. --b. > > > > --- > > fs/nfsd/nfssvc.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c > > index b2eef4112bc2..82ba034fa579 100644 > > --- a/fs/nfsd/nfssvc.c > > +++ b/fs/nfsd/nfssvc.c > > @@ -84,7 +84,7 @@ DEFINE_MUTEX(nfsd_mutex); > > * version 4.1 DRC caches. > > * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage. > > */ > > -spinlock_t nfsd_drc_lock; > > +DEFINE_SPINLOCK(nfsd_drc_lock); > > unsigned long nfsd_drc_max_mem; > > unsigned long nfsd_drc_mem_used; > > > > @@ -563,7 +563,6 @@ static void set_max_drc(void) > > nfsd_drc_max_mem = (nr_free_buffer_pages() > > >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE; > > nfsd_drc_mem_used = 0; > > - spin_lock_init(&nfsd_drc_lock); > > dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem); > > } > > > > > > -- > Chuck Lever > >
Hello- > On Apr 6, 2021, at 8:08 AM, Huang Guobin <huangguobin4@huawei.com> wrote: > > From: Guobin Huang <huangguobin4@huawei.com> > > spinlock can be initialized automatically with DEFINE_SPINLOCK() > rather than explicitly calling spin_lock_init(). > > Reported-by: Hulk Robot <hulkci@huawei.com> > Signed-off-by: Guobin Huang <huangguobin4@huawei.com> This change has been pushed to the for-next topic branch in git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git > --- > fs/nfsd/nfssvc.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c > index b2eef4112bc2..82ba034fa579 100644 > --- a/fs/nfsd/nfssvc.c > +++ b/fs/nfsd/nfssvc.c > @@ -84,7 +84,7 @@ DEFINE_MUTEX(nfsd_mutex); > * version 4.1 DRC caches. > * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage. > */ > -spinlock_t nfsd_drc_lock; > +DEFINE_SPINLOCK(nfsd_drc_lock); > unsigned long nfsd_drc_max_mem; > unsigned long nfsd_drc_mem_used; > > @@ -563,7 +563,6 @@ static void set_max_drc(void) > nfsd_drc_max_mem = (nr_free_buffer_pages() > >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE; > nfsd_drc_mem_used = 0; > - spin_lock_init(&nfsd_drc_lock); > dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem); > } > > -- Chuck Lever
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index b2eef4112bc2..82ba034fa579 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -84,7 +84,7 @@ DEFINE_MUTEX(nfsd_mutex); * version 4.1 DRC caches. * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage. */ -spinlock_t nfsd_drc_lock; +DEFINE_SPINLOCK(nfsd_drc_lock); unsigned long nfsd_drc_max_mem; unsigned long nfsd_drc_mem_used; @@ -563,7 +563,6 @@ static void set_max_drc(void) nfsd_drc_max_mem = (nr_free_buffer_pages() >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE; nfsd_drc_mem_used = 0; - spin_lock_init(&nfsd_drc_lock); dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem); }