| Message ID | 20180608050344.27572-1-natechancellor@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | dm bufio: avoid false-positive Wmaybe-uninitialized warning | expand |
On Thu, Jun 07, 2018 at 10:03:44PM -0700, Nathan Chancellor wrote: > From: Arnd Bergmann <arnd@arndb.de> > > commit 590347e4000356f55eb10b03ced2686bd74dab40 upstream. > > gcc-6.3 and earlier show a new warning after a seemingly unrelated > change to the arm64 PAGE_KERNEL definition: > > In file included from drivers/md/dm-bufio.c:14:0: > drivers/md/dm-bufio.c: In function 'alloc_buffer': > include/linux/sched/mm.h:182:56: warning: 'noio_flag' may be used uninitialized in this function [-Wmaybe-uninitialized] > current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; > ^ > > The same warning happened earlier on linux-3.18 for MIPS and I did a > workaround for that, but now it's come back. > > gcc-7 and newer are apparently smart enough to figure this out, and > other architectures don't show it, so the best I could come up with is > to rework the caller slightly in a way that makes it obvious enough to > all arm64 compilers what is happening here. > > Fixes: 41acec624087 ("arm64: kpti: Make use of nG dependent on arm64_kernel_unmapped_at_el0()") > Link: https://patchwork.kernel.org/patch/9692829/ > Cc: stable@vger.kernel.org > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > [snitzer: moved declarations inside conditional, altered vmalloc return] > Signed-off-by: Mike Snitzer <snitzer@redhat.com> > [nc: Backport to 4.9, adjust context for lack of 19809c2da28a] > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- > drivers/md/dm-bufio.c | 17 +++++++---------- > 1 file changed, 7 insertions(+), 10 deletions(-) > > diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c > index 3ec647e8b9c6..35fd57fdeba9 100644 > --- a/drivers/md/dm-bufio.c > +++ b/drivers/md/dm-bufio.c > @@ -373,9 +373,6 @@ static void __cache_size_refresh(void) > static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, > enum data_mode *data_mode) > { > - unsigned noio_flag; > - void *ptr; > - > if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) { > *data_mode = DATA_MODE_SLAB; > return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask); > @@ -399,16 +396,16 @@ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, > * all allocations done by this process (including pagetables) are done > * as if GFP_NOIO was specified. > */ > + if (gfp_mask & __GFP_NORETRY) { > + unsigned noio_flag = memalloc_noio_save(); > + void *ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, > + PAGE_KERNEL); > > - if (gfp_mask & __GFP_NORETRY) > - noio_flag = memalloc_noio_save(); > - > - ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL); > - > - if (gfp_mask & __GFP_NORETRY) > memalloc_noio_restore(noio_flag); > + return ptr; > + } > > - return ptr; > + return __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL); > } > > /* > -- > 2.17.1 > Gah, sorry, forgot to add a prefix. This should only be applied to 4.9, it's already present in 4.14 and it isn't needed for 4.4. Cheers! Nathan
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index 3ec647e8b9c6..35fd57fdeba9 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -373,9 +373,6 @@ static void __cache_size_refresh(void) static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, enum data_mode *data_mode) { - unsigned noio_flag; - void *ptr; - if (c->block_size <= DM_BUFIO_BLOCK_SIZE_SLAB_LIMIT) { *data_mode = DATA_MODE_SLAB; return kmem_cache_alloc(DM_BUFIO_CACHE(c), gfp_mask); @@ -399,16 +396,16 @@ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, * all allocations done by this process (including pagetables) are done * as if GFP_NOIO was specified. */ + if (gfp_mask & __GFP_NORETRY) { + unsigned noio_flag = memalloc_noio_save(); + void *ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, + PAGE_KERNEL); - if (gfp_mask & __GFP_NORETRY) - noio_flag = memalloc_noio_save(); - - ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL); - - if (gfp_mask & __GFP_NORETRY) memalloc_noio_restore(noio_flag); + return ptr; + } - return ptr; + return __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL); } /*