[Patch 1/2] megaraid_sas: switch fw_outstanding to an atomic_t

From: Sumant Patro
Date: Fri May 26 2006 - 14:22:59 EST

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Hello All,

This patch( originally submitted by Christoph Hellwig) removes instance_lock
and changes fw_outstanding variable data type to atomic_t.

Patch is made against the latest git snapshot of scsi-misc-2.6 tree.

Thanks,

Sumant Patro

Signed-off-by: Sumant Patro <Sumant.Patro@xxxxxxxx>

diff -uprN linux-2.6.17-rc4-orig/Documentation/scsi/ChangeLog.megaraid_sas linux-2.6.17-rc4-new/Documentation/scsi/ChangeLog.megaraid_sas
--- linux-2.6.17-rc4-orig/Documentation/scsi/ChangeLog.megaraid_sas 2006-05-25 12:10:34.000000000 -0700
+++ linux-2.6.17-rc4-new/Documentation/scsi/ChangeLog.megaraid_sas 2006-05-25 18:00:02.000000000 -0700
@@ -1,3 +1,16 @@
+
+1 Release Date : Wed Feb 03 14:31:44 PST 2006 - Sumant Patro <Sumant.Patro@xxxxxxxx>
+2 Current Version : 00.00.02.04
+3 Older Version : 00.00.02.04
+
+i. Remove superflous instance_lock
+
+ gets rid of the otherwise superflous instance_lock and avoids an unsave
+ unsynchronized access in the error handler.
+
+ - Christoph Hellwig <hch@xxxxxx>
+
+
1 Release Date : Wed Feb 03 14:31:44 PST 2006 - Sumant Patro <Sumant.Patro@xxxxxxxx>
2 Current Version : 00.00.02.04
3 Older Version : 00.00.02.04
diff -uprN linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.c linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.c
--- linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.c 2006-05-25 12:06:03.000000000 -0700
+++ linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.c 2006-05-25 17:03:14.000000000 -0700
@@ -741,7 +741,6 @@ static int
megasas_queue_command(struct scsi_cmnd *scmd, void (*done) (struct scsi_cmnd *))
{
u32 frame_count;
- unsigned long flags;
struct megasas_cmd *cmd;
struct megasas_instance *instance;

@@ -776,9 +775,7 @@ megasas_queue_command(struct scsi_cmnd *
/*
* Issue the command to the FW
*/
- spin_lock_irqsave(&instance->instance_lock, flags);
- instance->fw_outstanding++;
- spin_unlock_irqrestore(&instance->instance_lock, flags);
+ atomic_inc(&instance->fw_outstanding);

instance->instancet->fire_cmd(cmd->frame_phys_addr ,cmd->frame_count-1,instance->reg_set);

@@ -826,19 +823,20 @@ static int megasas_wait_for_outstanding(

for (i = 0; i < wait_time; i++) {

- if (!instance->fw_outstanding)
+ int outstanding = atomic_read(&instance->fw_outstanding);
+
+ if (!outstanding)
break;

if (!(i % MEGASAS_RESET_NOTICE_INTERVAL)) {
printk(KERN_NOTICE "megasas: [%2d]waiting for %d "
- "commands to complete\n", i,
- instance->fw_outstanding);
+ "commands to complete\n",i,outstanding);
}

msleep(1000);
}

- if (instance->fw_outstanding) {
+ if (atomic_read(&instance->fw_outstanding)) {
instance->hw_crit_error = 1;
return FAILED;
}
@@ -1050,7 +1048,6 @@ megasas_complete_cmd(struct megasas_inst
{
int exception = 0;
struct megasas_header *hdr = &cmd->frame->hdr;
- unsigned long flags;

if (cmd->scmd) {
cmd->scmd->SCp.ptr = (char *)0;
@@ -1082,9 +1079,7 @@ megasas_complete_cmd(struct megasas_inst

if (exception) {

- spin_lock_irqsave(&instance->instance_lock, flags);
- instance->fw_outstanding--;
- spin_unlock_irqrestore(&instance->instance_lock, flags);
+ atomic_dec(&instance->fw_outstanding);

megasas_unmap_sgbuf(instance, cmd);
cmd->scmd->scsi_done(cmd->scmd);
@@ -1132,9 +1127,7 @@ megasas_complete_cmd(struct megasas_inst
break;
}

- spin_lock_irqsave(&instance->instance_lock, flags);
- instance->fw_outstanding--;
- spin_unlock_irqrestore(&instance->instance_lock, flags);
+ atomic_dec(&instance->fw_outstanding);

megasas_unmap_sgbuf(instance, cmd);
cmd->scmd->scsi_done(cmd->scmd);
@@ -2171,11 +2164,12 @@ megasas_probe_one(struct pci_dev *pdev,
*/
INIT_LIST_HEAD(&instance->cmd_pool);

+ atomic_set(&instance->fw_outstanding,0);
+
init_waitqueue_head(&instance->int_cmd_wait_q);
init_waitqueue_head(&instance->abort_cmd_wait_q);

spin_lock_init(&instance->cmd_pool_lock);
- spin_lock_init(&instance->instance_lock);

sema_init(&instance->aen_mutex, 1);
sema_init(&instance->ioctl_sem, MEGASAS_INT_CMDS);
diff -uprN linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.h linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.h
--- linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.h 2006-05-25 12:06:03.000000000 -0700
+++ linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.h 2006-05-25 17:04:02.000000000 -0700
@@ -1077,9 +1077,8 @@ struct megasas_instance {
struct pci_dev *pdev;
u32 unique_id;

- u32 fw_outstanding;
+ atomic_t fw_outstanding;
u32 hw_crit_error;
- spinlock_t instance_lock;

struct megasas_instance_template *instancet;
};

diff -uprN linux-2.6.17-rc4-orig/Documentation/scsi/ChangeLog.megaraid_sas linux-2.6.17-rc4-new/Documentation/scsi/ChangeLog.megaraid_sas
--- linux-2.6.17-rc4-orig/Documentation/scsi/ChangeLog.megaraid_sas 2006-05-25 12:10:34.000000000 -0700
+++ linux-2.6.17-rc4-new/Documentation/scsi/ChangeLog.megaraid_sas 2006-05-25 18:00:02.000000000 -0700
@@ -1,3 +1,16 @@
+
+1 Release Date : Wed Feb 03 14:31:44 PST 2006 - Sumant Patro <Sumant.Patro@xxxxxxxx>
+2 Current Version : 00.00.02.04
+3 Older Version : 00.00.02.04
+
+i. Remove superflous instance_lock
+
+ gets rid of the otherwise superflous instance_lock and avoids an unsave
+ unsynchronized access in the error handler.
+
+ - Christoph Hellwig <hch@xxxxxx>
+
+
1 Release Date : Wed Feb 03 14:31:44 PST 2006 - Sumant Patro <Sumant.Patro@xxxxxxxx>
2 Current Version : 00.00.02.04
3 Older Version : 00.00.02.04
diff -uprN linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.c linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.c
--- linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.c 2006-05-25 12:06:03.000000000 -0700
+++ linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.c 2006-05-25 17:03:14.000000000 -0700
@@ -741,7 +741,6 @@ static int
megasas_queue_command(struct scsi_cmnd *scmd, void (*done) (struct scsi_cmnd *))
{
u32 frame_count;
- unsigned long flags;
struct megasas_cmd *cmd;
struct megasas_instance *instance;

@@ -776,9 +775,7 @@ megasas_queue_command(struct scsi_cmnd *
/*
* Issue the command to the FW
*/
- spin_lock_irqsave(&instance->instance_lock, flags);
- instance->fw_outstanding++;
- spin_unlock_irqrestore(&instance->instance_lock, flags);
+ atomic_inc(&instance->fw_outstanding);

instance->instancet->fire_cmd(cmd->frame_phys_addr ,cmd->frame_count-1,instance->reg_set);

@@ -826,19 +823,20 @@ static int megasas_wait_for_outstanding(

for (i = 0; i < wait_time; i++) {

- if (!instance->fw_outstanding)
+ int outstanding = atomic_read(&instance->fw_outstanding);
+
+ if (!outstanding)
break;

if (!(i % MEGASAS_RESET_NOTICE_INTERVAL)) {
printk(KERN_NOTICE "megasas: [%2d]waiting for %d "
- "commands to complete\n", i,
- instance->fw_outstanding);
+ "commands to complete\n",i,outstanding);
}

msleep(1000);
}

- if (instance->fw_outstanding) {
+ if (atomic_read(&instance->fw_outstanding)) {
instance->hw_crit_error = 1;
return FAILED;
}
@@ -1050,7 +1048,6 @@ megasas_complete_cmd(struct megasas_inst
{
int exception = 0;
struct megasas_header *hdr = &cmd->frame->hdr;
- unsigned long flags;

if (cmd->scmd) {
cmd->scmd->SCp.ptr = (char *)0;
@@ -1082,9 +1079,7 @@ megasas_complete_cmd(struct megasas_inst

if (exception) {

- spin_lock_irqsave(&instance->instance_lock, flags);
- instance->fw_outstanding--;
- spin_unlock_irqrestore(&instance->instance_lock, flags);
+ atomic_dec(&instance->fw_outstanding);

megasas_unmap_sgbuf(instance, cmd);
cmd->scmd->scsi_done(cmd->scmd);
@@ -1132,9 +1127,7 @@ megasas_complete_cmd(struct megasas_inst
break;
}

- spin_lock_irqsave(&instance->instance_lock, flags);
- instance->fw_outstanding--;
- spin_unlock_irqrestore(&instance->instance_lock, flags);
+ atomic_dec(&instance->fw_outstanding);

megasas_unmap_sgbuf(instance, cmd);
cmd->scmd->scsi_done(cmd->scmd);
@@ -2171,11 +2164,12 @@ megasas_probe_one(struct pci_dev *pdev,
*/
INIT_LIST_HEAD(&instance->cmd_pool);

+ atomic_set(&instance->fw_outstanding,0);
+
init_waitqueue_head(&instance->int_cmd_wait_q);
init_waitqueue_head(&instance->abort_cmd_wait_q);

spin_lock_init(&instance->cmd_pool_lock);
- spin_lock_init(&instance->instance_lock);

sema_init(&instance->aen_mutex, 1);
sema_init(&instance->ioctl_sem, MEGASAS_INT_CMDS);
diff -uprN linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.h linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.h
--- linux-2.6.17-rc4-orig/drivers/scsi/megaraid/megaraid_sas.h 2006-05-25 12:06:03.000000000 -0700
+++ linux-2.6.17-rc4-new/drivers/scsi/megaraid/megaraid_sas.h 2006-05-25 17:04:02.000000000 -0700
@@ -1077,9 +1077,8 @@ struct megasas_instance {
struct pci_dev *pdev;
u32 unique_id;

- u32 fw_outstanding;
+ atomic_t fw_outstanding;
u32 hw_crit_error;
- spinlock_t instance_lock;

struct megasas_instance_template *instancet;
};

Next message: Christian Kujau: "Re: SCSI ABORT with 2.6.17-rc4-mm1"
Previous message: Frank Gevaerts: "usb-serial ipaq kernel problem"
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