On 2022/05/23 19:06, Lianbo Jiang wrote:
> Kernel commit 4e5cc99e1e48 ("blk-mq: manage hctx map via xarray") removed
> the "queue_hw_ctx" member from struct request_queue at Linux v5.18-rc1,
> and replaced it with a struct xarray "hctx_table".Without the patch,
more complex...
> the "dev -d|-D" options will print an error:
>
> crash> dev -d
> MAJOR GENDISK NAME REQUEST_QUEUE TOTAL READ WRITE
>
> dev: invalid structure member offset: request_queue_queue_hw_ctx
>
> With the patch:
> crash> dev -d
> MAJOR GENDISK NAME REQUEST_QUEUE TOTAL READ WRITE
> 8 ffff8e99d0a1ae00 sda ffff8e9c14c59980 10 6 4
>
> Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> ---
> defs.h | 1 +
> dev.c | 44 ++++++++++++++++++++++++++++++++++----------
> symbols.c | 2 ++
> 3 files changed, 37 insertions(+), 10 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index c1626bc79d59..1e435ffe5535 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2181,6 +2181,7 @@ struct offset_table { /* stash of commonly-used offsets */
> long blk_mq_tags_nr_reserved_tags;
> long blk_mq_tags_rqs;
> long blk_mq_tags_static_rqs;
> + long request_queue_hctx_table;
> };
>
> struct size_table { /* stash of commonly-used sizes */
> diff --git a/dev.c b/dev.c
> index 7e0b3d27888d..811414d93c94 100644
> --- a/dev.c
> +++ b/dev.c
> @@ -4406,24 +4406,46 @@ static void get_mq_diskio_from_hw_queues(ulong q, struct diskio *dio)
> uint cnt = 0;
> ulong addr = 0, hctx_addr = 0;
> ulong *hctx_array = NULL;
> + struct list_pair *lp = NULL;
> struct diskio tmp = {0};
>
> - addr = q + OFFSET(request_queue_nr_hw_queues);
> - readmem(addr, KVADDR, &cnt, sizeof(uint),
> - "request_queue.nr_hw_queues", FAULT_ON_ERROR);
> + if (MEMBER_EXISTS("request_queue", "hctx_table")) {
As MEMBER_OFFSET_INIT() was done, we can use VALID_MEMBER() macro,
which is faster than MEMBER_EXISTS(),
Thanks,
Kazu
> + addr = q + OFFSET(request_queue_hctx_table);
> + cnt = do_xarray(addr, XARRAY_COUNT, NULL);
> + lp = (struct list_pair *)GETBUF(sizeof(struct list_pair) * (cnt + 1));
> + if (!lp)
> + error(FATAL, "fail to get memory for list_pair.\n");
> + lp[0].index = cnt;
> + cnt = do_xarray(addr, XARRAY_GATHER, lp);
> + } else {
> + addr = q + OFFSET(request_queue_nr_hw_queues);
> + readmem(addr, KVADDR, &cnt, sizeof(uint),
> + "request_queue.nr_hw_queues", FAULT_ON_ERROR);
>
> - addr = q + OFFSET(request_queue_queue_hw_ctx);
> - readmem(addr, KVADDR, &hctx_addr, sizeof(void *),
> - "request_queue.queue_hw_ctx", FAULT_ON_ERROR);
> + addr = q + OFFSET(request_queue_queue_hw_ctx);
> + readmem(addr, KVADDR, &hctx_addr, sizeof(void *),
> + "request_queue.queue_hw_ctx", FAULT_ON_ERROR);
> + }
>
> hctx_array = (ulong *)GETBUF(sizeof(void *) * cnt);
> - if (!hctx_array)
> + if (!hctx_array) {
> + if (lp)
> + FREEBUF(lp);
> error(FATAL, "fail to get memory for the hctx_array\n");
> + }
> +
> + if (lp && hctx_array) {
> + uint i;
>
> - if (!readmem(hctx_addr, KVADDR, hctx_array, sizeof(void *) * cnt,
> + /* copy it from list_pair to hctx_array */
> + for (i = 0; i < cnt; i++) {
> + hctx_array[i] = (ulong)lp[i].value;
> + }
> + FREEBUF(lp);
> + } else if (!readmem(hctx_addr, KVADDR, hctx_array, sizeof(void *) * cnt,
> "request_queue.queue_hw_ctx[]", RETURN_ON_ERROR)) {
> - FREEBUF(hctx_array);
> - return;
> + FREEBUF(hctx_array);
> + return;
> }
>
> queue_for_each_hw_ctx(q, hctx_array, cnt, &tmp);
> @@ -4796,6 +4818,8 @@ void diskio_init(void)
> "request_queue", "queue_hw_ctx");
> MEMBER_OFFSET_INIT(request_queue_nr_hw_queues,
> "request_queue", "nr_hw_queues");
> + MEMBER_OFFSET_INIT(request_queue_hctx_table,
> + "request_queue", "hctx_table");
> MEMBER_OFFSET_INIT(blk_mq_ctx_rq_dispatched, "blk_mq_ctx",
> "rq_dispatched");
> MEMBER_OFFSET_INIT(blk_mq_ctx_rq_completed, "blk_mq_ctx",
> diff --git a/symbols.c b/symbols.c
> index c432469671a4..cc439e8eb636 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -10401,6 +10401,8 @@ dump_offset_table(char *spec, ulong makestruct)
> OFFSET(request_queue_queue_hw_ctx));
> fprintf(fp, " request_queue_nr_hw_queues: %ld\n",
> OFFSET(request_queue_nr_hw_queues));
> + fprintf(fp, " request_queue_hctx_table: %ld\n",
> + OFFSET(request_queue_hctx_table));
> fprintf(fp, " blk_mq_ctx_rq_dispatched: %ld\n",
> OFFSET(blk_mq_ctx_rq_dispatched));
> fprintf(fp, " blk_mq_ctx_rq_completed: %ld\n",
--
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