From 14042268045596a89f3fae3606389536d4784113 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Mon, 4 Dec 2023 11:42:58 -0500 Subject: 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 Reviewed-by: Eric Blake Acked-by: Kevin Wolf Message-ID: <20231204164259.1515217-4-stefanha@redhat.com> Signed-off-by: Kevin Wolf --- hw/scsi/scsi-disk.c | 23 ----------------------- 1 file changed, 23 deletions(-) (limited to 'hw/scsi/scsi-disk.c') diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c index 6691f5edb8..2c1bbb3530 100644 --- a/hw/scsi/scsi-disk.c +++ b/hw/scsi/scsi-disk.c @@ -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; @@ -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); } @@ -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; @@ -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. */ @@ -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; @@ -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. */ @@ -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; @@ -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) @@ -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; @@ -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) @@ -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; @@ -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; } @@ -1857,7 +1839,6 @@ done: 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) @@ -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) { @@ -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; -- cgit v1.2.3 From 10bcb0d996634aec642b000f05a72c93b652b2e6 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 5 Dec 2023 13:19:59 -0500 Subject: scsi: assert that callbacks run in the correct AioContext Since the removal of AioContext locking, the correctness of the code relies on running requests from a single AioContext at any given time. Add assertions that verify that callbacks are invoked in the correct AioContext. Signed-off-by: Stefan Hajnoczi Message-ID: <20231205182011.1976568-3-stefanha@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- hw/scsi/scsi-disk.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'hw/scsi/scsi-disk.c') diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c index 2c1bbb3530..a5048e0aaf 100644 --- a/hw/scsi/scsi-disk.c +++ b/hw/scsi/scsi-disk.c @@ -273,6 +273,10 @@ static void scsi_aio_complete(void *opaque, int ret) SCSIDiskReq *r = (SCSIDiskReq *)opaque; SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev); + /* The request must only run in the BlockBackend's AioContext */ + assert(blk_get_aio_context(s->qdev.conf.blk) == + qemu_get_current_aio_context()); + assert(r->req.aiocb != NULL); r->req.aiocb = NULL; @@ -370,8 +374,13 @@ static void scsi_dma_complete(void *opaque, int ret) static void scsi_read_complete_noio(SCSIDiskReq *r, int ret) { + SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev); uint32_t n; + /* The request must only run in the BlockBackend's AioContext */ + assert(blk_get_aio_context(s->qdev.conf.blk) == + qemu_get_current_aio_context()); + assert(r->req.aiocb == NULL); if (scsi_disk_req_check_error(r, ret, false)) { goto done; @@ -496,8 +505,13 @@ static void scsi_read_data(SCSIRequest *req) static void scsi_write_complete_noio(SCSIDiskReq *r, int ret) { + SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev); uint32_t n; + /* The request must only run in the BlockBackend's AioContext */ + assert(blk_get_aio_context(s->qdev.conf.blk) == + qemu_get_current_aio_context()); + assert (r->req.aiocb == NULL); if (scsi_disk_req_check_error(r, ret, false)) { goto done; -- cgit v1.2.3 From 4f36b1384756914a6c4ffe04080a96da149c4c03 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 5 Dec 2023 13:20:05 -0500 Subject: scsi: remove AioContext locking The AioContext lock no longer has any effect. Remove it. Signed-off-by: Stefan Hajnoczi Reviewed-by: Eric Blake Message-ID: <20231205182011.1976568-9-stefanha@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- hw/scsi/scsi-disk.c | 31 +++++-------------------------- 1 file changed, 5 insertions(+), 26 deletions(-) (limited to 'hw/scsi/scsi-disk.c') diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c index a5048e0aaf..61be3d395a 100644 --- a/hw/scsi/scsi-disk.c +++ b/hw/scsi/scsi-disk.c @@ -2339,14 +2339,10 @@ static void scsi_disk_reset(DeviceState *dev) { SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev.qdev, dev); uint64_t nb_sectors; - AioContext *ctx; scsi_device_purge_requests(&s->qdev, SENSE_CODE(RESET)); - ctx = blk_get_aio_context(s->qdev.conf.blk); - aio_context_acquire(ctx); blk_get_geometry(s->qdev.conf.blk, &nb_sectors); - aio_context_release(ctx); nb_sectors /= s->qdev.blocksize / BDRV_SECTOR_SIZE; if (nb_sectors) { @@ -2545,15 +2541,13 @@ static void scsi_unrealize(SCSIDevice *dev) static void scsi_hd_realize(SCSIDevice *dev, Error **errp) { SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev); - AioContext *ctx = NULL; + /* can happen for devices without drive. The error message for missing * backend will be issued in scsi_realize */ if (s->qdev.conf.blk) { - ctx = blk_get_aio_context(s->qdev.conf.blk); - aio_context_acquire(ctx); if (!blkconf_blocksizes(&s->qdev.conf, errp)) { - goto out; + return; } } s->qdev.blocksize = s->qdev.conf.logical_block_size; @@ -2562,16 +2556,11 @@ static void scsi_hd_realize(SCSIDevice *dev, Error **errp) s->product = g_strdup("QEMU HARDDISK"); } scsi_realize(&s->qdev, errp); -out: - if (ctx) { - aio_context_release(ctx); - } } static void scsi_cd_realize(SCSIDevice *dev, Error **errp) { SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev); - AioContext *ctx; int ret; uint32_t blocksize = 2048; @@ -2587,8 +2576,6 @@ static void scsi_cd_realize(SCSIDevice *dev, Error **errp) blocksize = dev->conf.physical_block_size; } - ctx = blk_get_aio_context(dev->conf.blk); - aio_context_acquire(ctx); s->qdev.blocksize = blocksize; s->qdev.type = TYPE_ROM; s->features |= 1 << SCSI_DISK_F_REMOVABLE; @@ -2596,7 +2583,6 @@ static void scsi_cd_realize(SCSIDevice *dev, Error **errp) s->product = g_strdup("QEMU CD-ROM"); } scsi_realize(&s->qdev, errp); - aio_context_release(ctx); } @@ -2727,7 +2713,6 @@ static int get_device_type(SCSIDiskState *s) static void scsi_block_realize(SCSIDevice *dev, Error **errp) { SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev); - AioContext *ctx; int sg_version; int rc; @@ -2742,9 +2727,6 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp) "be removed in a future version"); } - ctx = blk_get_aio_context(s->qdev.conf.blk); - aio_context_acquire(ctx); - /* check we are using a driver managing SG_IO (version 3 and after) */ rc = blk_ioctl(s->qdev.conf.blk, SG_GET_VERSION_NUM, &sg_version); if (rc < 0) { @@ -2752,18 +2734,18 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp) if (rc != -EPERM) { error_append_hint(errp, "Is this a SCSI device?\n"); } - goto out; + return; } if (sg_version < 30000) { error_setg(errp, "scsi generic interface too old"); - goto out; + return; } /* get device type from INQUIRY data */ rc = get_device_type(s); if (rc < 0) { error_setg(errp, "INQUIRY failed"); - goto out; + return; } /* Make a guess for the block size, we'll fix it when the guest sends. @@ -2783,9 +2765,6 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp) scsi_realize(&s->qdev, errp); scsi_generic_read_device_inquiry(&s->qdev); - -out: - aio_context_release(ctx); } typedef struct SCSIBlockReq { -- cgit v1.2.3 From e7fc3c4a8cc3e729d178b95721d51ca95573ba91 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 5 Dec 2023 13:20:09 -0500 Subject: scsi: remove outdated AioContext lock comment The SCSI subsystem no longer uses the AioContext lock. Request processing runs exclusively in the BlockBackend's AioContext since "scsi: only access SCSIDevice->requests from one thread" and hence the lock is unnecessary. Signed-off-by: Stefan Hajnoczi Reviewed-by: Eric Blake Message-ID: <20231205182011.1976568-13-stefanha@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- hw/scsi/scsi-disk.c | 1 - 1 file changed, 1 deletion(-) (limited to 'hw/scsi/scsi-disk.c') diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c index 61be3d395a..2e7e1e9a1c 100644 --- a/hw/scsi/scsi-disk.c +++ b/hw/scsi/scsi-disk.c @@ -355,7 +355,6 @@ done: scsi_req_unref(&r->req); } -/* Called with AioContext lock held */ static void scsi_dma_complete(void *opaque, int ret) { SCSIDiskReq *r = (SCSIDiskReq *)opaque; -- cgit v1.2.3