| Message ID | 20181031113418.29796-4-anton.nefedov@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | discard blockstats | expand |
31.10.2018 14:34, Anton Nefedov wrote: > This adds some protection from accounting unitialized cookie. uninitialized > That is, block_acct_failed/done without previous block_acct_start; > in that case, cookie probably holds values from previous operation. > > (Note: it might also be unitialized holding garbage value and there is and here. > still "< BLOCK_MAX_IOTYPE" assertion for that. > So block_acct_failed/done without previous block_acct_start should be used > with caution.) > > Currently this is particularly useful in ide code where it's hard to > keep track whether the request started accounting or not. For example, > trim requests do the accounting separately. so, is it an existing bug? Could you please give an example in the code of such wrong (before the patch) accounting? > > Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com> > --- > include/block/accounting.h | 1 + > block/accounting.c | 6 ++++++ > 2 files changed, 7 insertions(+) > > diff --git a/include/block/accounting.h b/include/block/accounting.h > index ba8b04d572..878b4c3581 100644 > --- a/include/block/accounting.h > +++ b/include/block/accounting.h > @@ -33,6 +33,7 @@ typedef struct BlockAcctTimedStats BlockAcctTimedStats; > typedef struct BlockAcctStats BlockAcctStats; > > enum BlockAcctType { > + BLOCK_ACCT_NONE = 0, > BLOCK_ACCT_READ, > BLOCK_ACCT_WRITE, > BLOCK_ACCT_FLUSH, > diff --git a/block/accounting.c b/block/accounting.c > index 70a3d9a426..8d41c8a83a 100644 > --- a/block/accounting.c > +++ b/block/accounting.c > @@ -195,6 +195,10 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, > > assert(cookie->type < BLOCK_MAX_IOTYPE); > > + if (cookie->type == BLOCK_ACCT_NONE) { > + return; > + } > + > qemu_mutex_lock(&stats->lock); > > if (failed) { > @@ -217,6 +221,8 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, > } > > qemu_mutex_unlock(&stats->lock); > + > + cookie->type = BLOCK_ACCT_NONE; > } > > void block_acct_done(BlockAcctStats *stats, BlockAcctCookie *cookie) >
On 23/11/2018 7:04 PM, Vladimir Sementsov-Ogievskiy wrote: > 31.10.2018 14:34, Anton Nefedov wrote: >> This adds some protection from accounting unitialized cookie. > > uninitialized > fixed >> That is, block_acct_failed/done without previous block_acct_start; >> in that case, cookie probably holds values from previous operation. >> >> (Note: it might also be unitialized holding garbage value and there is > > and here. > fixed >> still "< BLOCK_MAX_IOTYPE" assertion for that. >> So block_acct_failed/done without previous block_acct_start should be used >> with caution.) >> >> Currently this is particularly useful in ide code where it's hard to >> keep track whether the request started accounting or not. For example, >> trim requests do the accounting separately. > > so, is it an existing bug? Could you please give an example in the code of such wrong (before the patch) accounting? > e.g. look at ide_dma_cb()->ide_handle_rw_error() call. In IDE_DMA_TRIM case, the cookie is never initialized, but it is block_acct_failed()-ed anyway. >> >> Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com> >> --- >> include/block/accounting.h | 1 + >> block/accounting.c | 6 ++++++ >> 2 files changed, 7 insertions(+) >> >> diff --git a/include/block/accounting.h b/include/block/accounting.h >> index ba8b04d572..878b4c3581 100644 >> --- a/include/block/accounting.h >> +++ b/include/block/accounting.h >> @@ -33,6 +33,7 @@ typedef struct BlockAcctTimedStats BlockAcctTimedStats; >> typedef struct BlockAcctStats BlockAcctStats; >> >> enum BlockAcctType { >> + BLOCK_ACCT_NONE = 0, >> BLOCK_ACCT_READ, >> BLOCK_ACCT_WRITE, >> BLOCK_ACCT_FLUSH, >> diff --git a/block/accounting.c b/block/accounting.c >> index 70a3d9a426..8d41c8a83a 100644 >> --- a/block/accounting.c >> +++ b/block/accounting.c >> @@ -195,6 +195,10 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, >> >> assert(cookie->type < BLOCK_MAX_IOTYPE); >> >> + if (cookie->type == BLOCK_ACCT_NONE) { >> + return; >> + } >> + >> qemu_mutex_lock(&stats->lock); >> >> if (failed) { >> @@ -217,6 +221,8 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, >> } >> >> qemu_mutex_unlock(&stats->lock); >> + >> + cookie->type = BLOCK_ACCT_NONE; >> } >> >> void block_acct_done(BlockAcctStats *stats, BlockAcctCookie *cookie) >> > >
diff --git a/include/block/accounting.h b/include/block/accounting.h index ba8b04d572..878b4c3581 100644 --- a/include/block/accounting.h +++ b/include/block/accounting.h @@ -33,6 +33,7 @@ typedef struct BlockAcctTimedStats BlockAcctTimedStats; typedef struct BlockAcctStats BlockAcctStats; enum BlockAcctType { + BLOCK_ACCT_NONE = 0, BLOCK_ACCT_READ, BLOCK_ACCT_WRITE, BLOCK_ACCT_FLUSH, diff --git a/block/accounting.c b/block/accounting.c index 70a3d9a426..8d41c8a83a 100644 --- a/block/accounting.c +++ b/block/accounting.c @@ -195,6 +195,10 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, assert(cookie->type < BLOCK_MAX_IOTYPE); + if (cookie->type == BLOCK_ACCT_NONE) { + return; + } + qemu_mutex_lock(&stats->lock); if (failed) { @@ -217,6 +221,8 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, } qemu_mutex_unlock(&stats->lock); + + cookie->type = BLOCK_ACCT_NONE; } void block_acct_done(BlockAcctStats *stats, BlockAcctCookie *cookie)
This adds some protection from accounting unitialized cookie. That is, block_acct_failed/done without previous block_acct_start; in that case, cookie probably holds values from previous operation. (Note: it might also be unitialized holding garbage value and there is still "< BLOCK_MAX_IOTYPE" assertion for that. So block_acct_failed/done without previous block_acct_start should be used with caution.) Currently this is particularly useful in ide code where it's hard to keep track whether the request started accounting or not. For example, trim requests do the accounting separately. Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com> --- include/block/accounting.h | 1 + block/accounting.c | 6 ++++++ 2 files changed, 7 insertions(+)