* [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes()
@ 2024-01-30 0:27 Stefan Hajnoczi
2024-01-30 8:31 ` Philippe Mathieu-Daudé
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Stefan Hajnoczi @ 2024-01-30 0:27 UTC (permalink / raw)
To: qemu-devel
Cc: John Snow, Kevin Wolf, qemu-block, Hanna Reitz, Stefan Hajnoczi,
Xiang Zheng
The following expression is incorrect because blk_pread_nonzeroes()
deals in units of bytes, not sectors:
bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS)
^^^^^^^
BDRV_REQUEST_MAX_BYTES is the appropriate constant.
Fixes: a4b15a8b9ef2 ("pflash: Only read non-zero parts of backend image")
Cc: Xiang Zheng <zhengxiang9@huawei.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/block/block.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/block/block.c b/hw/block/block.c
index 9f52ee6e72..ff503002aa 100644
--- a/hw/block/block.c
+++ b/hw/block/block.c
@@ -30,7 +30,7 @@ static int blk_pread_nonzeroes(BlockBackend *blk, hwaddr size, void *buf)
BlockDriverState *bs = blk_bs(blk);
for (;;) {
- bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS);
+ bytes = MIN(size - offset, BDRV_REQUEST_MAX_BYTES);
if (bytes <= 0) {
return 0;
}
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes()
2024-01-30 0:27 [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes() Stefan Hajnoczi
@ 2024-01-30 8:31 ` Philippe Mathieu-Daudé
2024-01-30 21:18 ` Stefan Hajnoczi
2024-02-01 11:37 ` Michael Tokarev
2 siblings, 0 replies; 6+ messages in thread
From: Philippe Mathieu-Daudé @ 2024-01-30 8:31 UTC (permalink / raw)
To: Stefan Hajnoczi, qemu-devel, qemu-stable
Cc: John Snow, Kevin Wolf, qemu-block, Hanna Reitz, Xiang Zheng
On 30/1/24 01:27, Stefan Hajnoczi wrote:
> The following expression is incorrect because blk_pread_nonzeroes()
> deals in units of bytes, not sectors:
>
> bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS)
> ^^^^^^^
>
> BDRV_REQUEST_MAX_BYTES is the appropriate constant.
>
> Fixes: a4b15a8b9ef2 ("pflash: Only read non-zero parts of backend image")
> Cc: Xiang Zheng <zhengxiang9@huawei.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> hw/block/block.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/block/block.c b/hw/block/block.c
> index 9f52ee6e72..ff503002aa 100644
> --- a/hw/block/block.c
> +++ b/hw/block/block.c
> @@ -30,7 +30,7 @@ static int blk_pread_nonzeroes(BlockBackend *blk, hwaddr size, void *buf)
> BlockDriverState *bs = blk_bs(blk);
>
> for (;;) {
> - bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS);
> + bytes = MIN(size - offset, BDRV_REQUEST_MAX_BYTES);
> if (bytes <= 0) {
> return 0;
> }
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes()
2024-01-30 0:27 [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes() Stefan Hajnoczi
2024-01-30 8:31 ` Philippe Mathieu-Daudé
@ 2024-01-30 21:18 ` Stefan Hajnoczi
2024-02-01 11:37 ` Michael Tokarev
2 siblings, 0 replies; 6+ messages in thread
From: Stefan Hajnoczi @ 2024-01-30 21:18 UTC (permalink / raw)
To: qemu-devel; +Cc: John Snow, Kevin Wolf, qemu-block, Hanna Reitz, Xiang Zheng
[-- Attachment #1: Type: text/plain, Size: 717 bytes --]
On Mon, Jan 29, 2024 at 07:27:12PM -0500, Stefan Hajnoczi wrote:
> The following expression is incorrect because blk_pread_nonzeroes()
> deals in units of bytes, not sectors:
>
> bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS)
> ^^^^^^^
>
> BDRV_REQUEST_MAX_BYTES is the appropriate constant.
>
> Fixes: a4b15a8b9ef2 ("pflash: Only read non-zero parts of backend image")
> Cc: Xiang Zheng <zhengxiang9@huawei.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> hw/block/block.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Thanks, applied to my block tree:
https://gitlab.com/stefanha/qemu/commits/block
Stefan
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes()
2024-01-30 0:27 [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes() Stefan Hajnoczi
2024-01-30 8:31 ` Philippe Mathieu-Daudé
2024-01-30 21:18 ` Stefan Hajnoczi
@ 2024-02-01 11:37 ` Michael Tokarev
2024-02-08 21:21 ` Stefan Hajnoczi
2 siblings, 1 reply; 6+ messages in thread
From: Michael Tokarev @ 2024-02-01 11:37 UTC (permalink / raw)
To: Stefan Hajnoczi, qemu-devel
Cc: John Snow, Kevin Wolf, qemu-block, Hanna Reitz, Xiang Zheng
30.01.2024 03:27, Stefan Hajnoczi wrote:
> The following expression is incorrect because blk_pread_nonzeroes()
> deals in units of bytes, not sectors:
>
> bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS)
> ^^^^^^^
>
> BDRV_REQUEST_MAX_BYTES is the appropriate constant.
>
> Fixes: a4b15a8b9ef2 ("pflash: Only read non-zero parts of backend image")
> Cc: Xiang Zheng <zhengxiang9@huawei.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> hw/block/block.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/block/block.c b/hw/block/block.c
> index 9f52ee6e72..ff503002aa 100644
> --- a/hw/block/block.c
> +++ b/hw/block/block.c
> @@ -30,7 +30,7 @@ static int blk_pread_nonzeroes(BlockBackend *blk, hwaddr size, void *buf)
> BlockDriverState *bs = blk_bs(blk);
>
> for (;;) {
> - bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS);
> + bytes = MIN(size - offset, BDRV_REQUEST_MAX_BYTES);
Hmm. This smells like a -stable material, but you know better not
to Cc: qemu-stable@ for unrelated stuff... Is it not for stable?
Thanks,
/mjt
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes()
2024-02-01 11:37 ` Michael Tokarev
@ 2024-02-08 21:21 ` Stefan Hajnoczi
2024-02-09 7:44 ` Michael Tokarev
0 siblings, 1 reply; 6+ messages in thread
From: Stefan Hajnoczi @ 2024-02-08 21:21 UTC (permalink / raw)
To: Michael Tokarev
Cc: Stefan Hajnoczi, qemu-devel, John Snow, Kevin Wolf, qemu-block,
Hanna Reitz, Xiang Zheng
On Thu, 1 Feb 2024 at 06:37, Michael Tokarev <mjt@tls.msk.ru> wrote:
>
> 30.01.2024 03:27, Stefan Hajnoczi wrote:
> > The following expression is incorrect because blk_pread_nonzeroes()
> > deals in units of bytes, not sectors:
> >
> > bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS)
> > ^^^^^^^
> >
> > BDRV_REQUEST_MAX_BYTES is the appropriate constant.
> >
> > Fixes: a4b15a8b9ef2 ("pflash: Only read non-zero parts of backend image")
> > Cc: Xiang Zheng <zhengxiang9@huawei.com>
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > ---
> > hw/block/block.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/hw/block/block.c b/hw/block/block.c
> > index 9f52ee6e72..ff503002aa 100644
> > --- a/hw/block/block.c
> > +++ b/hw/block/block.c
> > @@ -30,7 +30,7 @@ static int blk_pread_nonzeroes(BlockBackend *blk, hwaddr size, void *buf)
> > BlockDriverState *bs = blk_bs(blk);
> >
> > for (;;) {
> > - bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS);
> > + bytes = MIN(size - offset, BDRV_REQUEST_MAX_BYTES);
>
> Hmm. This smells like a -stable material, but you know better not
> to Cc: qemu-stable@ for unrelated stuff... Is it not for stable?
This is not a user-visible bug. The code still works with the smaller
MAX_SECTORS value thanks to the loop.
It doesn't hurt to include it in -stable but I also think it doesn't
help :-). It's just an inconsistency in the code.
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes()
2024-02-08 21:21 ` Stefan Hajnoczi
@ 2024-02-09 7:44 ` Michael Tokarev
0 siblings, 0 replies; 6+ messages in thread
From: Michael Tokarev @ 2024-02-09 7:44 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Stefan Hajnoczi, qemu-devel, John Snow, Kevin Wolf, qemu-block,
Hanna Reitz, Xiang Zheng
09.02.2024 00:21, Stefan Hajnoczi wrote:
> On Thu, 1 Feb 2024 at 06:37, Michael Tokarev <mjt@tls.msk.ru> wrote:
>>> for (;;) {
>>> - bytes = MIN(size - offset, BDRV_REQUEST_MAX_SECTORS);
>>> + bytes = MIN(size - offset, BDRV_REQUEST_MAX_BYTES);
>>
>> Hmm. This smells like a -stable material, but you know better not
>> to Cc: qemu-stable@ for unrelated stuff... Is it not for stable?
>
> This is not a user-visible bug. The code still works with the smaller
> MAX_SECTORS value thanks to the loop.
Yeah, that's my thoughts exactly. Also, most of the time, the cap will
be `size' anyway, not MAX. Still thought I'd ask :)
Thank you for the confirmation!
/mjt
> It doesn't hurt to include it in -stable but I also think it doesn't
> help :-). It's just an inconsistency in the code.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2024-02-09 7:45 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2024-01-30 0:27 [PATCH] pflash: fix sectors vs bytes confusion in blk_pread_nonzeroes() Stefan Hajnoczi
2024-01-30 8:31 ` Philippe Mathieu-Daudé
2024-01-30 21:18 ` Stefan Hajnoczi
2024-02-01 11:37 ` Michael Tokarev
2024-02-08 21:21 ` Stefan Hajnoczi
2024-02-09 7:44 ` Michael Tokarev
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