Re: [PATCH v5 10/10] scsi: Implement blk_mq_ops.show_rq()

[Bart Van Assche]

On Tue, 2017-04-25 at 14:39 -0700, Omar Sandoval wrote:
> On Tue, Apr 25, 2017 at 01:37:45PM -0700, Bart Van Assche wrote:
> > Show the SCSI CDB, .eh_eflags and .result for pending SCSI commands
> > in /sys/kernel/debug/block/*/mq/*/dispatch and */rq_list.
> 
> Only thing I noticed was that the only other caller I see has buf[70].
> No idea if that's a meaningful number. For the sake of this not getting
> bike-shedded to death,

Neither length is sufficient to avoid truncation of e.g. ATA pass-through
commands or commands with variable length CDBs. However, from the point of
view of debugging queue lockups the most useful information in a SCSI
command are the first two bytes of the CDB. The chosen buffer length is
definitely enough to make sure that these two bytes will be reported.

Bart.

Re: [PATCH v5 10/10] scsi: Implement blk_mq_ops.show_rq()

[Omar Sandoval]

On Tue, Apr 25, 2017 at 01:37:45PM -0700, Bart Van Assche wrote:
> Show the SCSI CDB, .eh_eflags and .result for pending SCSI commands
> in /sys/kernel/debug/block/*/mq/*/dispatch and */rq_list.

Only thing I noticed was that the only other caller I see has buf[70].
No idea if that's a meaningful number. For the sake of this not getting
bike-shedded to death,

Reviewed-by: Omar Sandoval 

> Signed-off-by: Bart Van Assche 
> Cc: Martin K. Petersen 
> Cc: James Bottomley 
> Cc: Omar Sandoval 
> Cc: Hannes Reinecke 
> Cc: 
> ---
>  drivers/scsi/Makefile   |  1 +
>  drivers/scsi/scsi_debugfs.c | 13 +
>  drivers/scsi/scsi_debugfs.h |  4 
>  drivers/scsi/scsi_lib.c |  4 
>  4 files changed, 22 insertions(+)
>  create mode 100644 drivers/scsi/scsi_debugfs.c
>  create mode 100644 drivers/scsi/scsi_debugfs.h
> 
> diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile
> index fc2855565a51..93dbe58c47c8 100644
> --- a/drivers/scsi/Makefile
> +++ b/drivers/scsi/Makefile
> @@ -166,6 +166,7 @@ scsi_mod-y+= scsi_scan.o 
> scsi_sysfs.o scsi_devinfo.o
>  scsi_mod-$(CONFIG_SCSI_NETLINK)  += scsi_netlink.o
>  scsi_mod-$(CONFIG_SYSCTL)+= scsi_sysctl.o
>  scsi_mod-$(CONFIG_SCSI_PROC_FS)  += scsi_proc.o
> +scsi_mod-$(CONFIG_BLK_DEBUG_FS)  += scsi_debugfs.o
>  scsi_mod-y   += scsi_trace.o scsi_logging.o
>  scsi_mod-$(CONFIG_PM)+= scsi_pm.o
>  scsi_mod-$(CONFIG_SCSI_DH)   += scsi_dh.o
> diff --git a/drivers/scsi/scsi_debugfs.c b/drivers/scsi/scsi_debugfs.c
> new file mode 100644
> index ..f831c23fdee3
> --- /dev/null
> +++ b/drivers/scsi/scsi_debugfs.c
> @@ -0,0 +1,13 @@
> +#include 
> +#include 
> +#include 
> +#include "scsi_debugfs.h"
> +
> +void scsi_show_rq(struct seq_file *m, struct request *rq)
> +{
> + struct scsi_cmnd *cmd = container_of(scsi_req(rq), typeof(*cmd), req);
> + char buf[64];
> +
> + __scsi_format_command(buf, sizeof(buf), cmd->cmnd, cmd->cmd_len);
> + seq_printf(m, ", .cmd=%s", buf);
> +}
> diff --git a/drivers/scsi/scsi_debugfs.h b/drivers/scsi/scsi_debugfs.h
> new file mode 100644
> index ..951b043e82d0
> --- /dev/null
> +++ b/drivers/scsi/scsi_debugfs.h
> @@ -0,0 +1,4 @@
> +struct request;
> +struct seq_file;
> +
> +void scsi_show_rq(struct seq_file *m, struct request *rq);
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index abc391e00f7d..1c3e87d6c48f 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -34,6 +34,7 @@
>  
>  #include 
>  
> +#include "scsi_debugfs.h"
>  #include "scsi_priv.h"
>  #include "scsi_logging.h"
>  
> @@ -2157,6 +2158,9 @@ static const struct blk_mq_ops scsi_mq_ops = {
>   .queue_rq   = scsi_queue_rq,
>   .complete   = scsi_softirq_done,
>   .timeout= scsi_timeout,
> +#ifdef CONFIG_BLK_DEBUG_FS
> + .show_rq= scsi_show_rq,
> +#endif
>   .init_request   = scsi_init_request,
>   .exit_request   = scsi_exit_request,
>   .map_queues = scsi_map_queues,
> -- 
> 2.12.2
> 

[PATCH v5 10/10] scsi: Implement blk_mq_ops.show_rq()

[Bart Van Assche]

Show the SCSI CDB, .eh_eflags and .result for pending SCSI commands
in /sys/kernel/debug/block/*/mq/*/dispatch and */rq_list.

Signed-off-by: Bart Van Assche 
Cc: Martin K. Petersen 
Cc: James Bottomley 
Cc: Omar Sandoval 
Cc: Hannes Reinecke 
Cc: 
---
 drivers/scsi/Makefile   |  1 +
 drivers/scsi/scsi_debugfs.c | 13 +
 drivers/scsi/scsi_debugfs.h |  4 
 drivers/scsi/scsi_lib.c |  4 
 4 files changed, 22 insertions(+)
 create mode 100644 drivers/scsi/scsi_debugfs.c
 create mode 100644 drivers/scsi/scsi_debugfs.h

diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile
index fc2855565a51..93dbe58c47c8 100644
--- a/drivers/scsi/Makefile
+++ b/drivers/scsi/Makefile
@@ -166,6 +166,7 @@ scsi_mod-y  += scsi_scan.o scsi_sysfs.o 
scsi_devinfo.o
 scsi_mod-$(CONFIG_SCSI_NETLINK)+= scsi_netlink.o
 scsi_mod-$(CONFIG_SYSCTL)  += scsi_sysctl.o
 scsi_mod-$(CONFIG_SCSI_PROC_FS)+= scsi_proc.o
+scsi_mod-$(CONFIG_BLK_DEBUG_FS)+= scsi_debugfs.o
 scsi_mod-y += scsi_trace.o scsi_logging.o
 scsi_mod-$(CONFIG_PM)  += scsi_pm.o
 scsi_mod-$(CONFIG_SCSI_DH) += scsi_dh.o
diff --git a/drivers/scsi/scsi_debugfs.c b/drivers/scsi/scsi_debugfs.c
new file mode 100644
index ..f831c23fdee3
--- /dev/null
+++ b/drivers/scsi/scsi_debugfs.c
@@ -0,0 +1,13 @@
+#include 
+#include 
+#include 
+#include "scsi_debugfs.h"
+
+void scsi_show_rq(struct seq_file *m, struct request *rq)
+{
+   struct scsi_cmnd *cmd = container_of(scsi_req(rq), typeof(*cmd), req);
+   char buf[64];
+
+   __scsi_format_command(buf, sizeof(buf), cmd->cmnd, cmd->cmd_len);
+   seq_printf(m, ", .cmd=%s", buf);
+}
diff --git a/drivers/scsi/scsi_debugfs.h b/drivers/scsi/scsi_debugfs.h
new file mode 100644
index ..951b043e82d0
--- /dev/null
+++ b/drivers/scsi/scsi_debugfs.h
@@ -0,0 +1,4 @@
+struct request;
+struct seq_file;
+
+void scsi_show_rq(struct seq_file *m, struct request *rq);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index abc391e00f7d..1c3e87d6c48f 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -34,6 +34,7 @@
 
 #include 
 
+#include "scsi_debugfs.h"
 #include "scsi_priv.h"
 #include "scsi_logging.h"
 
@@ -2157,6 +2158,9 @@ static const struct blk_mq_ops scsi_mq_ops = {
.queue_rq   = scsi_queue_rq,
.complete   = scsi_softirq_done,
.timeout= scsi_timeout,
+#ifdef CONFIG_BLK_DEBUG_FS
+   .show_rq= scsi_show_rq,
+#endif
.init_request   = scsi_init_request,
.exit_request   = scsi_exit_request,
.map_queues = scsi_map_queues,
-- 
2.12.2