CEE reported an issue that "dev -d/-D" reports incorrect value of read/write: crash> dev -d MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC SYNC 8 ffff90528df86000 sda ffff9052a3d61800 144 144 0 8 ffff905280718c00 sdb ffff9052a3d63c00 48 48 0 crash> epython rqlist ffff90528e94a5c0 sda is unknown, deadline: 89.992 (90) rq_alloc: 0.196 ffff90528e92f700 sda is unknown, deadline: 89.998 (90) rq_alloc: 0.202 ffff90528e95ccc0 sda is unknown, deadline: 89.999 (90) rq_alloc: 0.203 ffff90528e968bc0 sdb is unknown, deadline: 89.997 (90) rq_alloc: 0.201 The value of 144 ASYNC is incorrect and epython rqlist only show 3 items for sda. The reason is, mq_check_inflight() may get the same rq multiple times during iteration, so they are counted repeatly. This patch will add a rq repetition check. After apply the patch: crash> dev -d MAJOR GENDISK NAME REQUEST_QUEUE TOTAL READ WRITE 8 ffff90528df86000 sda ffff9052a3d61800 3 3 0 8 ffff905280718c00 sdb ffff9052a3d63c00 1 1 0 Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; --- dev.c | 43 ++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 40 insertions(+), 3 deletions(-) diff --git a/dev.c b/dev.c index 9d38aef..b0434cf 100644 --- a/dev.c +++ b/dev.c @@ -4316,6 +4316,9 @@ struct bt_iter_data { ulong tags; uint reserved; uint nr_reserved_tags; + ulong **rq_list; + int *rq_list_len; + int *rq_list_cap; busy_tag_iter_fn *fn; void *data; }; @@ -4381,10 +4384,30 @@ static bool bt_iter(uint bitnr, void *data) if (!readmem(addr, KVADDR, &rq, sizeof(ulong), "blk_mq_tags.rqs[]", RETURN_ON_ERROR)) return FALSE; + for (int i = 0; i < *iter_data->rq_list_len; i++) { + /* Skip the handled rq */ + if ((*iter_data->rq_list)[i] == rq) + return TRUE; + } + /* Mark the rq is handled */ + (*iter_data->rq_list)[(*iter_data->rq_list_len)++] = rq; + if (*iter_data->rq_list_len > *iter_data->rq_list_cap / 2) { + *iter_data->rq_list_cap <<= 1; + ulong *tmp = reallocarray(*iter_data->rq_list, + *iter_data->rq_list_cap, sizeof(ulong)); + if (!tmp) { + free(*iter_data->rq_list); + error(FATAL, "cannot reallocarray rq_list array"); + } + *iter_data->rq_list = tmp; + } + return iter_data->fn(rq, iter_data->data); } -static void bt_for_each(ulong q, ulong tags, ulong sbq, uint reserved, uint nr_resvd_tags, struct diskio *dio) +static void bt_for_each(ulong q, ulong tags, ulong sbq, uint reserved, + uint nr_resvd_tags, ulong **rq_list, int *rq_list_len, + int *rq_list_cap, struct diskio *dio) { struct sbitmap_context sc = {0}; struct mq_inflight mi = { @@ -4395,6 +4418,9 @@ static void bt_for_each(ulong q, ulong tags, ulong sbq, uint reserved, uint nr_r .tags = tags, .reserved = reserved, .nr_reserved_tags = nr_resvd_tags, + .rq_list = rq_list, + .rq_list_len = rq_list_len, + .rq_list_cap = rq_list_cap, .fn = mq_check_inflight, .data = &mi, }; @@ -4407,10 +4433,18 @@ static void queue_for_each_hw_ctx(ulong q, ulong *hctx, uint cnt, struct diskio { uint i; int bitmap_tags_is_ptr = 0; + ulong *rq_list; + int rq_list_len = 0; + int rq_list_cap = 1; if (MEMBER_TYPE("blk_mq_tags", "bitmap_tags") == TYPE_CODE_PTR) bitmap_tags_is_ptr = 1; + rq_list = calloc(rq_list_cap, sizeof(ulong)); + if (!rq_list) { + error(FATAL, "cannot malloc rq_list array"); + } + for (i = 0; i < cnt; i++) { ulong addr = 0, tags = 0; uint nr_reserved_tags = 0; @@ -4432,15 +4466,18 @@ static void queue_for_each_hw_ctx(ulong q, ulong *hctx, uint cnt, struct diskio !readmem(addr, KVADDR, &addr, sizeof(ulong), "blk_mq_tags.bitmap_tags", RETURN_ON_ERROR)) break; - bt_for_each(q, tags, addr, 1, nr_reserved_tags, dio); + bt_for_each(q, tags, addr, 1, nr_reserved_tags, &rq_list, + &rq_list_len, &rq_list_cap, dio); } addr = tags + OFFSET(blk_mq_tags_bitmap_tags); if (bitmap_tags_is_ptr && !readmem(addr, KVADDR, &addr, sizeof(ulong), "blk_mq_tags.bitmap_tags", RETURN_ON_ERROR)) break; - bt_for_each(q, tags, addr, 0, nr_reserved_tags, dio); + bt_for_each(q, tags, addr, 1, nr_reserved_tags, &rq_list, + &rq_list_len, &rq_list_cap, dio); } + free(rq_list); } static void get_mq_diskio_from_hw_queues(ulong q, struct diskio *dio) -- 2.47.0