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scsi: don't lock AioContext in I/O code path 
blk_aio_*() doesn't require the AioContext lock and the SCSI subsystem's
internal state also does not anymore.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231204164259.1515217-4-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Stefan Hajnoczi authored and Kevin Wolf committed Dec 21, 2023
1 parent 99af49d commit 264553e
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Showing 2 changed files with 3 additions and 40 deletions.
23 changes: 0 additions & 23 deletions hw/scsi/scsi-disk.c
View file
Expand Up @@ -273,8 +273,6 @@ static void scsi_aio_complete(void *opaque, int ret)
SCSIDiskReq *r = (SCSIDiskReq *)opaque;
SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

assert(r->req.aiocb != NULL);
r->req.aiocb = NULL;

Expand All @@ -286,7 +284,6 @@ static void scsi_aio_complete(void *opaque, int ret)
scsi_req_complete(&r->req, GOOD);

done:
aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
scsi_req_unref(&r->req);
}

Expand Down Expand Up @@ -394,8 +391,6 @@ static void scsi_read_complete(void *opaque, int ret)
SCSIDiskReq *r = (SCSIDiskReq *)opaque;
SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

assert(r->req.aiocb != NULL);
r->req.aiocb = NULL;

Expand All @@ -406,7 +401,6 @@ static void scsi_read_complete(void *opaque, int ret)
trace_scsi_disk_read_complete(r->req.tag, r->qiov.size);
}
scsi_read_complete_noio(r, ret);
aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
}

/* Actually issue a read to the block device. */
Expand Down Expand Up @@ -448,8 +442,6 @@ static void scsi_do_read_cb(void *opaque, int ret)
SCSIDiskReq *r = (SCSIDiskReq *)opaque;
SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

assert (r->req.aiocb != NULL);
r->req.aiocb = NULL;

Expand All @@ -459,7 +451,6 @@ static void scsi_do_read_cb(void *opaque, int ret)
block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
}
scsi_do_read(opaque, ret);
aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
}

/* Read more data from scsi device into buffer. */
Expand Down Expand Up @@ -533,8 +524,6 @@ static void scsi_write_complete(void * opaque, int ret)
SCSIDiskReq *r = (SCSIDiskReq *)opaque;
SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

assert (r->req.aiocb != NULL);
r->req.aiocb = NULL;

Expand All @@ -544,7 +533,6 @@ static void scsi_write_complete(void * opaque, int ret)
block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
}
scsi_write_complete_noio(r, ret);
aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
}

static void scsi_write_data(SCSIRequest *req)
Expand Down Expand Up @@ -1742,8 +1730,6 @@ static void scsi_unmap_complete(void *opaque, int ret)
SCSIDiskReq *r = data->r;
SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

assert(r->req.aiocb != NULL);
r->req.aiocb = NULL;

Expand All @@ -1754,7 +1740,6 @@ static void scsi_unmap_complete(void *opaque, int ret)
block_acct_done(blk_get_stats(s->qdev.conf.blk), &r->acct);
scsi_unmap_complete_noio(data, ret);
}
aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
}

static void scsi_disk_emulate_unmap(SCSIDiskReq *r, uint8_t *inbuf)
Expand Down Expand Up @@ -1822,8 +1807,6 @@ static void scsi_write_same_complete(void *opaque, int ret)
SCSIDiskReq *r = data->r;
SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

assert(r->req.aiocb != NULL);
r->req.aiocb = NULL;

Expand All @@ -1847,7 +1830,6 @@ static void scsi_write_same_complete(void *opaque, int ret)
data->sector << BDRV_SECTOR_BITS,
&data->qiov, 0,
scsi_write_same_complete, data);
aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
return;
}

Expand All @@ -1857,7 +1839,6 @@ static void scsi_write_same_complete(void *opaque, int ret)
scsi_req_unref(&r->req);
qemu_vfree(data->iov.iov_base);
g_free(data);
aio_context_release(blk_get_aio_context(s->qdev.conf.blk));
}

static void scsi_disk_emulate_write_same(SCSIDiskReq *r, uint8_t *inbuf)
Expand Down Expand Up @@ -2810,7 +2791,6 @@ static void scsi_block_sgio_complete(void *opaque, int ret)
{
SCSIBlockReq *req = (SCSIBlockReq *)opaque;
SCSIDiskReq *r = &req->req;
SCSIDevice *s = r->req.dev;
sg_io_hdr_t *io_hdr = &req->io_header;

if (ret == 0) {
Expand All @@ -2827,13 +2807,10 @@ static void scsi_block_sgio_complete(void *opaque, int ret)
}

if (ret > 0) {
aio_context_acquire(blk_get_aio_context(s->conf.blk));
if (scsi_handle_rw_error(r, ret, true)) {
aio_context_release(blk_get_aio_context(s->conf.blk));
scsi_req_unref(&r->req);
return;
}
aio_context_release(blk_get_aio_context(s->conf.blk));

/* Ignore error. */
ret = 0;
Expand Down
20 changes: 3 additions & 17 deletions hw/scsi/scsi-generic.c
View file
Expand Up @@ -109,15 +109,11 @@ static void scsi_command_complete_noio(SCSIGenericReq *r, int ret)
static void scsi_command_complete(void *opaque, int ret)
{
SCSIGenericReq *r = (SCSIGenericReq *)opaque;
SCSIDevice *s = r->req.dev;

aio_context_acquire(blk_get_aio_context(s->conf.blk));

assert(r->req.aiocb != NULL);
r->req.aiocb = NULL;

scsi_command_complete_noio(r, ret);
aio_context_release(blk_get_aio_context(s->conf.blk));
}

static int execute_command(BlockBackend *blk,
Expand Down Expand Up @@ -274,14 +270,12 @@ static void scsi_read_complete(void * opaque, int ret)
SCSIDevice *s = r->req.dev;
int len;

aio_context_acquire(blk_get_aio_context(s->conf.blk));

assert(r->req.aiocb != NULL);
r->req.aiocb = NULL;

if (ret || r->req.io_canceled) {
scsi_command_complete_noio(r, ret);
goto done;
return;
}

len = r->io_header.dxfer_len - r->io_header.resid;
Expand Down Expand Up @@ -320,7 +314,7 @@ static void scsi_read_complete(void * opaque, int ret)
r->io_header.status != GOOD ||
len == 0) {
scsi_command_complete_noio(r, 0);
goto done;
return;
}

/* Snoop READ CAPACITY output to set the blocksize. */
Expand Down Expand Up @@ -356,9 +350,6 @@ static void scsi_read_complete(void * opaque, int ret)
req_complete:
scsi_req_data(&r->req, len);
scsi_req_unref(&r->req);

done:
aio_context_release(blk_get_aio_context(s->conf.blk));
}

/* Read more data from scsi device into buffer. */
Expand Down Expand Up @@ -391,14 +382,12 @@ static void scsi_write_complete(void * opaque, int ret)

trace_scsi_generic_write_complete(ret);

aio_context_acquire(blk_get_aio_context(s->conf.blk));

assert(r->req.aiocb != NULL);
r->req.aiocb = NULL;

if (ret || r->req.io_canceled) {
scsi_command_complete_noio(r, ret);
goto done;
return;
}

if (r->req.cmd.buf[0] == MODE_SELECT && r->req.cmd.buf[4] == 12 &&
Expand All @@ -408,9 +397,6 @@ static void scsi_write_complete(void * opaque, int ret)
}

scsi_command_complete_noio(r, ret);

done:
aio_context_release(blk_get_aio_context(s->conf.blk));
}

/* Write data to a scsi device. Returns nonzero on failure.
Expand Down

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