On 07/13/2014 02:50 PM, Christoph Hellwig wrote: > [email protected] wrote ... >> diff --git a/fs/direct-io.c b/fs/direct-io.c >> index 98040ba388ac..c0a9854d2bc7 100644 >> --- a/fs/direct-io.c >> +++ b/fs/direct-io.c >> @@ -910,7 +910,8 @@ static int do_direct_IO(struct dio *dio, struct >> dio_submit *sdio, >> >> while (sdio->block_in_file < sdio->final_block_in_request) { >> struct page *page; >> - size_t from, to; >> + size_t from = 0; >> + size_t to = 0; >> page = dio_get_page(dio, sdio, &from, &to); >> if (IS_ERR(page)) { >> ret = PTR_ERR(page); > Looks good to me, > > Reviewed-by: Christoph Hellwig <[email protected]> > > Al, can you pick this up? It's the only warnings in many of my usual > kernel builds at the moment. > <>
Paul Bolle <[email protected]> wrote ... <> > @@ -911,11 +907,15 @@ static int do_direct_IO(struct dio *dio, struct > dio_submit *sdio, > while (sdio->block_in_file < sdio->final_block_in_request) { > struct page *page; > size_t from, to; > - page = dio_get_page(dio, sdio, &from, &to); > + > + page = dio_get_page(dio, sdio); > if (IS_ERR(page)) { > ret = PTR_ERR(page); > goto out; > } > + from = sdio->head ? 0 : sdio->from; > + to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; > + sdio->head++; > > while (from < to) { > unsigned this_chunk_bytes; /* # of bytes mapped */ <> This is the wrong fix. GCC is wrong here. As shown by Paul Bolle if you move the from / to set from dio_get_page() to here the warning goes away. The minimal fix must use uninitialized_var() in this case. See patch below But I think the proper fix Is the one Paul Bolle <[email protected]> sent (above) ---- From: Boaz Harrosh <[email protected]> Date: Wed, 16 Jul 2014 20:02:29 +0300 Subject: [PATCH] do_direct_IO: Fix compiler warning MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This fixes ../fs/direct-io.c: In function ‘do_blockdev_direct_IO’: ../fs/direct-io.c:1011:12: warning: ‘from’ may be used uninitialized in this function [-Wmaybe-uninitialized] u = (to - from) >> blkbits; ^ ../fs/direct-io.c:1011:12: warning: ‘to’ may be used uninitialized in this function [-Wmaybe-uninitialized] u = (to - from) >> blkbits; I use: gcc version 4.8.3 20140624 (Red Hat 4.8.3-1) GCC is wrong here so we should use the uninitialized_var() macro and not silence it with = 0; Signed-off-by: Boaz Harrosh <[email protected]> --- fs/direct-io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index 98040ba..156e6f0 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -910,7 +910,8 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, while (sdio->block_in_file < sdio->final_block_in_request) { struct page *page; - size_t from, to; + size_t uninitialized_var(from), uninitialized_var(to); + page = dio_get_page(dio, sdio, &from, &to); if (IS_ERR(page)) { ret = PTR_ERR(page); -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
