RE: [PATCH 1/3] mpt3sas: Eliminate conditional locking in mpt3sas_scsih_issue_tm()

From: Chaitra Basappa
Date: Fri Aug 05 2016 - 00:29:33 EST

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Hi,
Please consider this patch as Acked-by: Chaitra P B
<chaitra.basappa@xxxxxxxxxxxx>

Thanks,
Chaitra

-----Original Message-----
From: Calvin Owens [mailto:calvinowens@xxxxxx]
Sent: Friday, July 29, 2016 10:08 AM
To: Sathya Prakash; Chaitra P B; Suganath Prabu Subramani; James E.J.
Bottomley; Martin K. Petersen
Cc: MPT-FusionLinux.pdl@xxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx;
linux-kernel@xxxxxxxxxxxxxxx; kernel-team@xxxxxx; Calvin Owens
Subject: [PATCH 1/3] mpt3sas: Eliminate conditional locking in
mpt3sas_scsih_issue_tm()

This flag that conditionally acquires the mutex is confusing and prone to
bugginess: refactor it into two separate function calls, and make the
unlocked one complain if it's called outside the mutex.

Signed-off-by: Calvin Owens <calvinowens@xxxxxx>
---
drivers/scsi/mpt3sas/mpt3sas_base.h | 16 +++------
drivers/scsi/mpt3sas/mpt3sas_ctl.c | 5 ++-
drivers/scsi/mpt3sas/mpt3sas_scsih.c | 66
+++++++++++++++++-------------------
3 files changed, 38 insertions(+), 49 deletions(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.h
b/drivers/scsi/mpt3sas/mpt3sas_base.h
index eb7f5b0..f0baafd 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.h
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.h
@@ -794,16 +794,6 @@ struct reply_post_struct {
dma_addr_t reply_post_free_dma;
};

-/**
- * enum mutex_type - task management mutex type
- * @TM_MUTEX_OFF: mutex is not required becuase calling function is
acquiring it
- * @TM_MUTEX_ON: mutex is required
- */
-enum mutex_type {
- TM_MUTEX_OFF = 0,
- TM_MUTEX_ON = 1,
-};
-
typedef void (*MPT3SAS_FLUSH_RUNNING_CMDS)(struct MPT3SAS_ADAPTER *ioc);
/**
* struct MPT3SAS_ADAPTER - per adapter struct @@ -1291,7 +1281,11 @@
void mpt3sas_scsih_reset_handler(struct MPT3SAS_ADAPTER *ioc, int
reset_phase);

int mpt3sas_scsih_issue_tm(struct MPT3SAS_ADAPTER *ioc, u16 handle,
uint channel, uint id, uint lun, u8 type, u16 smid_task,
- ulong timeout, enum mutex_type m_type);
+ ulong timeout);
+int mpt3sas_scsih_issue_locked_tm(struct MPT3SAS_ADAPTER *ioc, u16
handle,
+ uint channel, uint id, uint lun, u8 type, u16 smid_task,
+ ulong timeout);
+
void mpt3sas_scsih_set_tm_flag(struct MPT3SAS_ADAPTER *ioc, u16 handle);
void mpt3sas_scsih_clear_tm_flag(struct MPT3SAS_ADAPTER *ioc, u16 handle);
void mpt3sas_expander_remove(struct MPT3SAS_ADAPTER *ioc, u64
sas_address); diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c
b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
index 7d00f09..75ae533 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
@@ -1001,10 +1001,9 @@ _ctl_do_mpt_command(struct MPT3SAS_ADAPTER *ioc,
struct mpt3_ioctl_command karg,
ioc->name,

le16_to_cpu(mpi_request->FunctionDependent1));
mpt3sas_halt_firmware(ioc);
- mpt3sas_scsih_issue_tm(ioc,
+ mpt3sas_scsih_issue_locked_tm(ioc,
le16_to_cpu(mpi_request->FunctionDependent1),
0, 0,
- 0, MPI2_SCSITASKMGMT_TASKTYPE_TARGET_RESET, 0,
30,
- TM_MUTEX_ON);
+ 0, MPI2_SCSITASKMGMT_TASKTYPE_TARGET_RESET, 0,
30);
} else
mpt3sas_base_hard_reset_handler(ioc, CAN_SLEEP,
FORCE_BIG_HAMMER);
diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index acabe48..c93a7ba 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -2201,7 +2201,6 @@ mpt3sas_scsih_clear_tm_flag(struct MPT3SAS_ADAPTER
*ioc, u16 handle)
* @type: MPI2_SCSITASKMGMT_TASKTYPE__XXX (defined in mpi2_init.h)
* @smid_task: smid assigned to the task
* @timeout: timeout in seconds
- * @m_type: TM_MUTEX_ON or TM_MUTEX_OFF
* Context: user
*
* A generic API for sending task management requests to firmware.
@@ -2212,8 +2211,7 @@ mpt3sas_scsih_clear_tm_flag(struct MPT3SAS_ADAPTER
*ioc, u16 handle)
*/
int
mpt3sas_scsih_issue_tm(struct MPT3SAS_ADAPTER *ioc, u16 handle, uint
channel,
- uint id, uint lun, u8 type, u16 smid_task, ulong timeout,
- enum mutex_type m_type)
+ uint id, uint lun, u8 type, u16 smid_task, ulong timeout)
{
Mpi2SCSITaskManagementRequest_t *mpi_request;
Mpi2SCSITaskManagementReply_t *mpi_reply; @@ -2224,21 +2222,19 @@
mpt3sas_scsih_issue_tm(struct MPT3SAS_ADAPTER *ioc, u16 handle, uint
channel,
int rc;
u16 msix_task = 0;

- if (m_type == TM_MUTEX_ON)
- mutex_lock(&ioc->tm_cmds.mutex);
+ lockdep_assert_held(&ioc->tm_cmds.mutex);
+
if (ioc->tm_cmds.status != MPT3_CMD_NOT_USED) {
pr_info(MPT3SAS_FMT "%s: tm_cmd busy!!!\n",
__func__, ioc->name);
- rc = FAILED;
- goto err_out;
+ return FAILED;
}

if (ioc->shost_recovery || ioc->remove_host ||
ioc->pci_error_recovery) {
pr_info(MPT3SAS_FMT "%s: host reset in progress!\n",
__func__, ioc->name);
- rc = FAILED;
- goto err_out;
+ return FAILED;
}

ioc_state = mpt3sas_base_get_iocstate(ioc, 0); @@ -2247,8 +2243,7
@@ mpt3sas_scsih_issue_tm(struct MPT3SAS_ADAPTER *ioc, u16 handle, uint
channel,
"unexpected doorbell active!\n", ioc->name));
rc = mpt3sas_base_hard_reset_handler(ioc, CAN_SLEEP,
FORCE_BIG_HAMMER);
- rc = (!rc) ? SUCCESS : FAILED;
- goto err_out;
+ return (!rc) ? SUCCESS : FAILED;
}

if ((ioc_state & MPI2_IOC_STATE_MASK) == MPI2_IOC_STATE_FAULT) {
@@ -2256,16 +2251,14 @@ mpt3sas_scsih_issue_tm(struct MPT3SAS_ADAPTER
*ioc, u16 handle, uint channel,
MPI2_DOORBELL_DATA_MASK);
rc = mpt3sas_base_hard_reset_handler(ioc, CAN_SLEEP,
FORCE_BIG_HAMMER);
- rc = (!rc) ? SUCCESS : FAILED;
- goto err_out;
+ return (!rc) ? SUCCESS : FAILED;
}

smid = mpt3sas_base_get_smid_hpr(ioc, ioc->tm_cb_idx);
if (!smid) {
pr_err(MPT3SAS_FMT "%s: failed obtaining a smid\n",
ioc->name, __func__);
- rc = FAILED;
- goto err_out;
+ return FAILED;
}

if (type == MPI2_SCSITASKMGMT_TASKTYPE_ABORT_TASK)
@@ -2302,9 +2295,7 @@ mpt3sas_scsih_issue_tm(struct MPT3SAS_ADAPTER *ioc,
u16 handle, uint channel,
rc = mpt3sas_base_hard_reset_handler(ioc,
CAN_SLEEP,
FORCE_BIG_HAMMER);
rc = (!rc) ? SUCCESS : FAILED;
- ioc->tm_cmds.status = MPT3_CMD_NOT_USED;
- mpt3sas_scsih_clear_tm_flag(ioc, handle);
- goto err_out;
+ goto out;
}
}

@@ -2356,17 +2347,23 @@ mpt3sas_scsih_issue_tm(struct MPT3SAS_ADAPTER
*ioc, u16 handle, uint channel,
break;
}

+out:
mpt3sas_scsih_clear_tm_flag(ioc, handle);
ioc->tm_cmds.status = MPT3_CMD_NOT_USED;
- if (m_type == TM_MUTEX_ON)
- mutex_unlock(&ioc->tm_cmds.mutex);
-
return rc;
+}

- err_out:
- if (m_type == TM_MUTEX_ON)
- mutex_unlock(&ioc->tm_cmds.mutex);
- return rc;
+int mpt3sas_scsih_issue_locked_tm(struct MPT3SAS_ADAPTER *ioc, u16
handle,
+ uint channel, uint id, uint lun, u8 type, u16 smid_task, ulong
+timeout) {
+ int ret;
+
+ mutex_lock(&ioc->tm_cmds.mutex);
+ ret = mpt3sas_scsih_issue_tm(ioc, handle, channel, id, lun, type,
+ smid_task, timeout);
+ mutex_unlock(&ioc->tm_cmds.mutex);
+
+ return ret;
}

/**
@@ -2482,9 +2479,9 @@ scsih_abort(struct scsi_cmnd *scmd)
mpt3sas_halt_firmware(ioc);

handle = sas_device_priv_data->sas_target->handle;
- r = mpt3sas_scsih_issue_tm(ioc, handle, scmd->device->channel,
+ r = mpt3sas_scsih_issue_locked_tm(ioc, handle,
scmd->device->channel,
scmd->device->id, scmd->device->lun,
- MPI2_SCSITASKMGMT_TASKTYPE_ABORT_TASK, smid, 30, TM_MUTEX_ON);
+ MPI2_SCSITASKMGMT_TASKTYPE_ABORT_TASK, smid, 30);

out:
sdev_printk(KERN_INFO, scmd->device, "task abort: %s scmd(%p)\n",
@@ -2541,9 +2538,9 @@ scsih_dev_reset(struct scsi_cmnd *scmd)
goto out;
}

- r = mpt3sas_scsih_issue_tm(ioc, handle, scmd->device->channel,
+ r = mpt3sas_scsih_issue_locked_tm(ioc, handle,
scmd->device->channel,
scmd->device->id, scmd->device->lun,
- MPI2_SCSITASKMGMT_TASKTYPE_LOGICAL_UNIT_RESET, 0, 30,
TM_MUTEX_ON);
+ MPI2_SCSITASKMGMT_TASKTYPE_LOGICAL_UNIT_RESET, 0, 30);

out:
sdev_printk(KERN_INFO, scmd->device, "device reset: %s
scmd(%p)\n", @@ -2603,9 +2600,9 @@ scsih_target_reset(struct scsi_cmnd
*scmd)
goto out;
}

- r = mpt3sas_scsih_issue_tm(ioc, handle, scmd->device->channel,
+ r = mpt3sas_scsih_issue_locked_tm(ioc, handle,
scmd->device->channel,
scmd->device->id, 0, MPI2_SCSITASKMGMT_TASKTYPE_TARGET_RESET,
0,
- 30, TM_MUTEX_ON);
+ 30);

out:
starget_printk(KERN_INFO, starget, "target reset: %s scmd(%p)\n",
@@ -6089,8 +6086,7 @@ _scsih_sas_broadcast_primitive_event(struct
MPT3SAS_ADAPTER *ioc,

spin_unlock_irqrestore(&ioc->scsi_lookup_lock, flags);
r = mpt3sas_scsih_issue_tm(ioc, handle, 0, 0, lun,
- MPI2_SCSITASKMGMT_TASKTYPE_QUERY_TASK, smid, 30,
- TM_MUTEX_OFF);
+ MPI2_SCSITASKMGMT_TASKTYPE_QUERY_TASK, smid, 30);
if (r == FAILED) {
sdev_printk(KERN_WARNING, sdev,
"mpt3sas_scsih_issue_tm: FAILED when sending "
@@ -6130,8 +6126,8 @@ _scsih_sas_broadcast_primitive_event(struct
MPT3SAS_ADAPTER *ioc,
goto out_no_lock;

r = mpt3sas_scsih_issue_tm(ioc, handle, sdev->channel,
sdev->id,
- sdev->lun, MPI2_SCSITASKMGMT_TASKTYPE_ABORT_TASK,
smid, 30,
- TM_MUTEX_OFF);
+ sdev->lun, MPI2_SCSITASKMGMT_TASKTYPE_ABORT_TASK,
smid,
+ 30);
if (r == FAILED) {
sdev_printk(KERN_WARNING, sdev,
"mpt3sas_scsih_issue_tm: ABORT_TASK: FAILED :
"
--
2.8.0.rc2

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