Re: [PATCH scsi] Short the path length of scsi_cmd_to_driver()
On Thu, 2012-09-27 at 13:43 -0400, Martin K. Petersen wrote:
Li == Li Zhong zh...@linux.vnet.ibm.com writes:
@@ -845,8 +844,11 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd,
unsigned char *cmnd,
scsi_eh_restore_cmnd(scmd, ses);
-if (sdrv sdrv-eh_action)
-rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+if (scmd-request-cmd_type == REQ_TYPE_FS) {
+struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+if (sdrv-eh_action)
+rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+}
return rtn;
}
My only concern is whether our device lifetime rules guarantee that the
ULD is always attached when we service an error handling command?
Thank you, Martin, for the review.
I don't know much about scsi, it might take me some more time to have an
answer to the above question.
For now, if I understand correctly, maybe we could only do the
not-consistent behaviours bug fix? Or could we provide two versions of
scsi_cmd_to_driver(), one with NULL checking for scsi_send_eh_cmnd(),
one without the checking for scsi_finish_command()?
Thanks, Zhong
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Re: [PATCH scsi] Short the path length of scsi_cmd_to_driver()
On Thu, 2012-09-27 at 13:43 -0400, Martin K. Petersen wrote:
Li == Li Zhong zh...@linux.vnet.ibm.com writes:
@@ -845,8 +844,11 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd,
unsigned char *cmnd,
scsi_eh_restore_cmnd(scmd, ses);
-if (sdrv sdrv-eh_action)
-rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+if (scmd-request-cmd_type == REQ_TYPE_FS) {
+struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+if (sdrv-eh_action)
+rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+}
return rtn;
}
My only concern is whether our device lifetime rules guarantee that the
ULD is always attached when we service an error handling command?
Yes, they are. We can only get REQ_TYPE_FS through a filesystem, which
must be mounted on a block device, which is provided by the ULD. You
can't unmount with outstanding I/O (which people complain about when it
goes into error handling, I'll admit), so the ULD has to stay bound.
James
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[PATCH scsi] Short the path length of scsi_cmd_to_driver()
Hi James, Martin,
Here is the updated version, please help to review.
Thanks, Zhong
As suggested by James: this patch tries to short the path length of
scsi_cmd_to_driver(). As only REQ_TYPE_BLOCK_PC commands can be
submitted without a driver, so we could avoid the related NULL
checking, as long as we make sure we don't use it for REQ_TYPE_BLOCK_PC
type commands. Plus, this fixes a bug where you get different behaviors
from REQ_TYPE_BLOCK_PC commands when a driver is and isn't attached.
And Martin pointed out that we could have eh action be triggered for
REQ_TYPE_FS type only.
Signed-off-by: Li Zhong zh...@linux.vnet.ibm.com
---
drivers/scsi/scsi_error.c |8 +---
include/scsi/scsi_cmnd.h | 12 ++--
2 files changed, 7 insertions(+), 13 deletions(-)
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index de2337f..4001559 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -789,7 +789,6 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd,
unsigned char *cmnd,
int cmnd_size, int timeout, unsigned sense_bytes)
{
struct scsi_device *sdev = scmd-device;
- struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
struct Scsi_Host *shost = sdev-host;
DECLARE_COMPLETION_ONSTACK(done);
unsigned long timeleft;
@@ -845,8 +844,11 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd,
unsigned char *cmnd,
scsi_eh_restore_cmnd(scmd, ses);
- if (sdrv sdrv-eh_action)
- rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+ if (scmd-request-cmd_type == REQ_TYPE_FS) {
+ struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+ if (sdrv-eh_action)
+ rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+ }
return rtn;
}
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index ac06cc5..de5f5d8 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -132,18 +132,10 @@ struct scsi_cmnd {
unsigned char tag; /* SCSI-II queued command tag */
};
+/* make sure not to use it with REQ_TYPE_BLOCK_PC commands */
static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
{
- struct scsi_driver **sdp;
-
- if (!cmd-request-rq_disk)
- return NULL;
-
- sdp = (struct scsi_driver **)cmd-request-rq_disk-private_data;
- if (!sdp)
- return NULL;
-
- return *sdp;
+ return *(struct scsi_driver **)cmd-request-rq_disk-private_data;
}
extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);
--
1.7.7.6
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Re: [PATCH scsi] Short the path length of scsi_cmd_to_driver()
Li == Li Zhong zh...@linux.vnet.ibm.com writes:
@@ -845,8 +844,11 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd,
unsigned char *cmnd,
scsi_eh_restore_cmnd(scmd, ses);
- if (sdrv sdrv-eh_action)
- rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+ if (scmd-request-cmd_type == REQ_TYPE_FS) {
+ struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+ if (sdrv-eh_action)
+ rtn = sdrv-eh_action(scmd, cmnd, cmnd_size, rtn);
+ }
return rtn;
}
My only concern is whether our device lifetime rules guarantee that the
ULD is always attached when we service an error handling command?
--
Martin K. Petersen Oracle Linux Engineering
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