Messages in this thread | | | Date | Tue, 29 Oct 2019 09:05:21 +0100 | From | Greg KH <> | Subject | Re: [PATCH] drivers/staging/exfat: Replace binary semaphores for mutexes |
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On Sun, Oct 27, 2019 at 07:45:19PM -0700, Davidlohr Bueso wrote: > At a slight footprint cost (24 vs 32 bytes), mutexes are more optimal > than semaphores; it's also a nicer interface for mutual exclusion, > which is why they are encouraged over binary semaphores, when possible. > There is also lockdep support. > > For both v_sem and z_sem, their semantics imply traditional lock > ownership; that is, the lock owner is the same for both lock/unlock > operations and nothing is done in irq context. Therefore it is safe > to convert. > > Signed-off-by: Davidlohr Bueso <dave@stgolabs.net> > --- > This is part of further reducing semaphore users in the kernel. > > drivers/staging/exfat/exfat.h | 2 +- > drivers/staging/exfat/exfat_super.c | 84 ++++++++++++++++++------------------- > 2 files changed, 43 insertions(+), 43 deletions(-) > > diff --git a/drivers/staging/exfat/exfat.h b/drivers/staging/exfat/exfat.h > index 6c12f2d79f4d..95c02f55de60 100644 > --- a/drivers/staging/exfat/exfat.h > +++ b/drivers/staging/exfat/exfat.h > @@ -618,7 +618,7 @@ struct fs_info_t { > u32 dev_ejected; /* block device operation error flag */ > > struct fs_func *fs_func; > - struct semaphore v_sem; > + struct mutex v_mutex; > > /* FAT cache */ > struct buf_cache_t FAT_cache_array[FAT_CACHE_SIZE]; > diff --git a/drivers/staging/exfat/exfat_super.c b/drivers/staging/exfat/exfat_super.c > index 5f6caee819a6..c0b09b2dbe96 100644 > --- a/drivers/staging/exfat/exfat_super.c > +++ b/drivers/staging/exfat/exfat_super.c > @@ -283,7 +283,7 @@ static const struct dentry_operations exfat_dentry_ops = { > .d_compare = exfat_cmp, > }; > > -static DEFINE_SEMAPHORE(z_sem); > +static DEFINE_MUTEX(z_mutex); > > static inline void fs_sync(struct super_block *sb, bool do_sync) > { > @@ -352,11 +352,11 @@ static int ffsMountVol(struct super_block *sb) > > pr_info("[EXFAT] trying to mount...\n"); > > - down(&z_sem); > + mutex_lock(&z_mutex);
No tabs? :(
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