On 07/17/2014 12:48 PM, Paul Bolle wrote: > Boaz, > > On Thu, 2014-07-17 at 12:37 +0300, Boaz Harrosh wrote: >> From: Paul Bolle <[email protected]> >> >> The following warnings: >> >> fs/direct-io.c: In function ‘__blockdev_direct_IO’: >> fs/direct-io.c:1011:12: warning: ‘to’ may be used uninitialized in this >> function [-Wmaybe-uninitialized] >> fs/direct-io.c:913:16: note: ‘to’ was declared here >> fs/direct-io.c:1011:12: warning: ‘from’ may be used uninitialized in this >> function [-Wmaybe-uninitialized] >> fs/direct-io.c:913:10: note: ‘from’ was declared here >> >> are false positive because dio_get_page() either fails, or sets both >> 'from' and 'to'. >> >> Maybe it's better to move initializing "to" and "from" out of >> dio_get_page(). That _might_ make it easier for both the the reader and >> the compiler to understand what's going on. Something like this: >> >> Christoph Hellwig said ... >> The fix of moving the code defintively looks nicer, while I think >> uninitialized_var is horrible wart that won't get anywhere near my code. >> >> Boaz Harrosh I agree with Christoph and Paul >> >> Signed-off-by: Paul Bolle <[email protected]> > > This is simply not coorect!
Sorry you are absolutely right, I only saw this after "send", is why I ping you to make sure. I have reviewed it fully, your initial code is correct *and tested). Here is a new V2 patch without your sign-off Thanks Boaz > >> Signed-off-by: Boaz Harrosh <[email protected]> >> --- >> fs/direct-io.c | 14 +++++++------- >> 1 file changed, 7 insertions(+), 7 deletions(-) >> >> diff --git a/fs/direct-io.c b/fs/direct-io.c >> index 98040ba..2f024fc 100644 >> --- a/fs/direct-io.c >> +++ b/fs/direct-io.c >> @@ -198,9 +198,8 @@ static inline int dio_refill_pages(struct dio *dio, >> struct dio_submit *sdio) >> * L1 cache. >> */ >> static inline struct page *dio_get_page(struct dio *dio, >> - struct dio_submit *sdio, size_t *from, size_t *to) >> + struct dio_submit *sdio) >> { >> - int n; >> if (dio_pages_present(sdio) == 0) { >> int ret; >> >> @@ -209,10 +208,7 @@ static inline struct page *dio_get_page(struct dio *dio, >> return ERR_PTR(ret); >> BUG_ON(dio_pages_present(sdio) == 0); >> } >> - n = sdio->head++; >> - *from = n ? 0 : sdio->from; >> - *to = (n == sdio->tail - 1) ? sdio->to : PAGE_SIZE; >> - return dio->pages[n]; >> + return dio->pages[sdio->head]; >> } >> >> /** >> @@ -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 */ > > > Paul Bolle > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- 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/
