On Mon, Dec 04, 2017 at 04:38:08PM -0800, Bart Van Assche wrote:
> Since the next patch will make it possible that scsi_show_rq() gets
> called before the CDB pointer is changed into a non-NULL value,
> only show the CDB if the CDB pointer is not NULL. Additionally,
> show the request timeout and SCSI command flags. This patch also
> fixes a bug that was reported by Ming Lei. See also Ming Lei,
> scsi_debugfs: fix crash in scsi_show_rq(), linux-scsi, 7 November
> 2017 (https://marc.info/?l=linux-block&m=151006655317188).
Please cook a patch for fixing the crash issue only, since we need
to backport the fix to stable kernel.
>
> Signed-off-by: Bart Van Assche <bart.vanass...@wdc.com>
> Cc: James E.J. Bottomley <j...@linux.vnet.ibm.com>
> Cc: Martin K. Petersen <martin.peter...@oracle.com>
> Cc: Ming Lei <ming....@redhat.com>
> Cc: Christoph Hellwig <h...@lst.de>
> Cc: Hannes Reinecke <h...@suse.com>
> Cc: Johannes Thumshirn <jthumsh...@suse.de>
Please Cc: <sta...@vger.kernel.org>
> ---
> drivers/scsi/scsi_debugfs.c | 47
> ++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 42 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/scsi/scsi_debugfs.c b/drivers/scsi/scsi_debugfs.c
> index 01f08c03f2c1..37ed6bb8e6ec 100644
> --- a/drivers/scsi/scsi_debugfs.c
> +++ b/drivers/scsi/scsi_debugfs.c
> @@ -4,13 +4,50 @@
> #include <scsi/scsi_dbg.h>
> #include "scsi_debugfs.h"
>
> +#define SCSI_CMD_FLAG_NAME(name) [ilog2(SCMD_##name)] = #name
> +static const char *const scsi_cmd_flags[] = {
> + SCSI_CMD_FLAG_NAME(TAGGED),
> + SCSI_CMD_FLAG_NAME(UNCHECKED_ISA_DMA),
> + SCSI_CMD_FLAG_NAME(ZONE_WRITE_LOCK),
> + SCSI_CMD_FLAG_NAME(INITIALIZED),
> +};
> +#undef SCSI_CMD_FLAG_NAME
> +
> +static int scsi_flags_show(struct seq_file *m, const unsigned long flags,
> + const char *const *flag_name, int flag_name_count)
> +{
> + bool sep = false;
> + int i;
> +
> + for (i = 0; i < sizeof(flags) * BITS_PER_BYTE; i++) {
> + if (!(flags & BIT(i)))
> + continue;
> + if (sep)
> + seq_puts(m, "|");
> + sep = true;
> + if (i < flag_name_count && flag_name[i])
> + seq_puts(m, flag_name[i]);
> + else
> + seq_printf(m, "%d", i);
> + }
> + return 0;
> +}
> +
> void scsi_show_rq(struct seq_file *m, struct request *rq)
> {
> struct scsi_cmnd *cmd = container_of(scsi_req(rq), typeof(*cmd), req);
> - int msecs = jiffies_to_msecs(jiffies - cmd->jiffies_at_alloc);
> - char buf[80];
> + int alloc_ms = jiffies_to_msecs(jiffies - cmd->jiffies_at_alloc);
> + int timeout_ms = jiffies_to_msecs(rq->timeout);
> + const u8 *const cdb = READ_ONCE(cmd->cmnd);
> + char buf[80] = "(?)";
>
> - __scsi_format_command(buf, sizeof(buf), cmd->cmnd, cmd->cmd_len);
> - seq_printf(m, ", .cmd=%s, .retries=%d, allocated %d.%03d s ago", buf,
> - cmd->retries, msecs / 1000, msecs % 1000);
> + if (cdb)
> + __scsi_format_command(buf, sizeof(buf), cdb, cmd->cmd_len);
> + seq_printf(m, ", .cmd=%s, .retries=%d, .result = %#x, .flags=", buf,
> + cmd->retries, cmd->result);
> + scsi_flags_show(m, cmd->flags, scsi_cmd_flags,
> + ARRAY_SIZE(scsi_cmd_flags));
> + seq_printf(m, ", .timeout=%d.%03d, allocated %d.%03d s ago",
> + timeout_ms / 1000, timeout_ms % 1000,
> + alloc_ms / 1000, alloc_ms % 1000);
> }
> --
> 2.15.0
>
--
Ming
