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m25p80: do not put iovec on the stack

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When doing a read-modify-write cycle, QEMU uses the iovec after returning
from blk_aio_pwritev.  m25p80 puts the iovec on the stack of blk_aio_pwritev's
caller, which causes trouble in this case.  This has been a problem
since commit 243e6f6 ("m25p80: Switch to byte-based block access",
2016-05-12) started doing writes at a smaller granularity than 512 bytes.
In principle however it could have broken before when using -drive
if=mtd,cache=none on a disk with 4K native sectors.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-id: 1467138270-32481-3-git-send-email-clg@kaod.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Paolo Bonzini 2016-07-04 13:06:37 +01:00 committed by Peter Maydell
parent 7673bb4cd3
commit cace7b801d
1 changed files with 14 additions and 9 deletions
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23
hw/block/m25p80.c
View file

@ -447,6 +447,11 @@ static inline Manufacturer get_man(Flash *s)
static void blk_sync_complete(void *opaque, int ret)
{
QEMUIOVector *iov = opaque;
qemu_iovec_destroy(iov);
g_free(iov);
/* do nothing. Masters do not directly interact with the backing store,
* only the working copy so no mutexing required.
*/
@ -454,31 +459,31 @@ static void blk_sync_complete(void *opaque, int ret)
static void flash_sync_page(Flash *s, int page)
{
QEMUIOVector iov;
QEMUIOVector *iov = g_new(QEMUIOVector, 1);
if (!s->blk || blk_is_read_only(s->blk)) {
return;
}
qemu_iovec_init(&iov, 1);
qemu_iovec_add(&iov, s->storage + page * s->pi->page_size,
qemu_iovec_init(iov, 1);
qemu_iovec_add(iov, s->storage + page * s->pi->page_size,
s->pi->page_size);
blk_aio_pwritev(s->blk, page * s->pi->page_size, &iov, 0,
blk_sync_complete, NULL);
blk_aio_pwritev(s->blk, page * s->pi->page_size, iov, 0,
blk_sync_complete, iov);
}
static inline void flash_sync_area(Flash *s, int64_t off, int64_t len)
{
QEMUIOVector iov;
QEMUIOVector *iov = g_new(QEMUIOVector, 1);
if (!s->blk || blk_is_read_only(s->blk)) {
return;
}
assert(!(len % BDRV_SECTOR_SIZE));
qemu_iovec_init(&iov, 1);
qemu_iovec_add(&iov, s->storage + off, len);
blk_aio_pwritev(s->blk, off, &iov, 0, blk_sync_complete, NULL);
qemu_iovec_init(iov, 1);
qemu_iovec_add(iov, s->storage + off, len);
blk_aio_pwritev(s->blk, off, iov, 0, blk_sync_complete, iov);
}
static void flash_erase(Flash *s, int offset, FlashCMD cmd)