| Message ID | 1311148624-5640-6-git-send-email-freddy77@gmail.com |
|---|---|
| State | New |
| Headers | show |
Am 20.07.2011 09:57, schrieb Frediano Ziglio: > Signed-off-by: Frediano Ziglio <freddy77@gmail.com> > --- > block/qcow.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/block/qcow.c b/block/qcow.c > index 007fb57..8fd1ee5 100644 > --- a/block/qcow.c > +++ b/block/qcow.c > @@ -499,7 +499,6 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs, > int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, > int is_write, QCowAIOCB *acb) > { > - memset(acb, 0, sizeof(*acb)); > acb->bs = bs; > acb->sector_num = sector_num; > acb->qiov = qiov; > @@ -509,6 +508,7 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs, > if (is_write) > qemu_iovec_to_buffer(qiov, acb->buf); > } else { > + acb->orig_buf = NULL; > acb->buf = (uint8_t *)qiov->iov->iov_base; > } > acb->nb_sectors = nb_sectors; What does this fix? Removing the memset looks like changing code for no obvious reason. Is there any state in acb that must survive qcow_aio_setup? Kevin
2011/7/20 Kevin Wolf <kwolf@redhat.com>: > Am 20.07.2011 09:57, schrieb Frediano Ziglio: >> Signed-off-by: Frediano Ziglio <freddy77@gmail.com> >> --- >> block/qcow.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/block/qcow.c b/block/qcow.c >> index 007fb57..8fd1ee5 100644 >> --- a/block/qcow.c >> +++ b/block/qcow.c >> @@ -499,7 +499,6 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs, >> int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, >> int is_write, QCowAIOCB *acb) >> { >> - memset(acb, 0, sizeof(*acb)); >> acb->bs = bs; >> acb->sector_num = sector_num; >> acb->qiov = qiov; >> @@ -509,6 +508,7 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs, >> if (is_write) >> qemu_iovec_to_buffer(qiov, acb->buf); >> } else { >> + acb->orig_buf = NULL; >> acb->buf = (uint8_t *)qiov->iov->iov_base; >> } >> acb->nb_sectors = nb_sectors; > > What does this fix? Removing the memset looks like changing code for no > obvious reason. Is there any state in acb that must survive qcow_aio_setup? > > Kevin > No, this is not a fix, just an optimization, memset was used to clear entire structure but all fields are set by qcow_aio_setup, only orig_buf left. The comment, I must admit is terrible! And it's mine! I'll rewrite all comments, perhaps merge some commits and send all patches again. Frediano
diff --git a/block/qcow.c b/block/qcow.c index 007fb57..8fd1ee5 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -499,7 +499,6 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, int is_write, QCowAIOCB *acb) { - memset(acb, 0, sizeof(*acb)); acb->bs = bs; acb->sector_num = sector_num; acb->qiov = qiov; @@ -509,6 +508,7 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs, if (is_write) qemu_iovec_to_buffer(qiov, acb->buf); } else { + acb->orig_buf = NULL; acb->buf = (uint8_t *)qiov->iov->iov_base; } acb->nb_sectors = nb_sectors;
Signed-off-by: Frediano Ziglio <freddy77@gmail.com> --- block/qcow.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)