Re: [PATCH, RFC] Stop using tasklet in ds1374 RTC driver

From: Randy Vinson
Date: Mon Mar 27 2006 - 17:29:26 EST


Jean Delvare wrote:

Well I already have a patch for ds1374. This is basically a mix between
Randy's and my original patch: I've kept the dedicated workqueue as my
patch had, but preserved the in_interrupt() call as in Randy's. Here's
the result:

* * * * *

A tasklet is not suitable for what the ds1374 driver does: neither sleeping
nor mutex operations are allowed in tasklets, and ds1374_set_tlet may do
both.

We can use a workqueue instead, where both sleeping and mutex operations
are allowed.

Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
---
drivers/i2c/chips/ds1374.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

--- linux-2.6.16-git.orig/drivers/i2c/chips/ds1374.c 2006-03-27 18:25:17.000000000 +0200
+++ linux-2.6.16-git/drivers/i2c/chips/ds1374.c 2006-03-27 18:59:05.000000000 +0200
@@ -27,6 +27,7 @@
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/mutex.h>
+#include <linux/workqueue.h>
#define DS1374_REG_TOD0 0x00
#define DS1374_REG_TOD1 0x01
@@ -139,7 +140,7 @@
return t1;
}
-static void ds1374_set_tlet(ulong arg)
+static void ds1374_set_work(void *arg)
{
ulong t1, t2;
int limit = 10; /* arbitrary retry limit */
@@ -168,17 +169,18 @@
static ulong new_time;
-static DECLARE_TASKLET_DISABLED(ds1374_tasklet, ds1374_set_tlet,
- (ulong) & new_time);
+static struct workqueue_struct *ds1374_workqueue;
+
+static DECLARE_WORK(ds1374_work, ds1374_set_work, &new_time);
int ds1374_set_rtc_time(ulong nowtime)
{
new_time = nowtime;
if (in_interrupt())
- tasklet_schedule(&ds1374_tasklet);
+ queue_work(ds1374_workqueue, &ds1374_work);
else
- ds1374_set_tlet((ulong) & new_time);
+ ds1374_set_work(&new_time);
return 0;
}
@@ -204,6 +206,8 @@
client->adapter = adap;
client->driver = &ds1374_driver;
+ ds1374_workqueue = create_singlethread_workqueue("ds1374");
+
if ((rc = i2c_attach_client(client)) != 0) {
kfree(client);
return rc;
@@ -227,7 +231,7 @@
if ((rc = i2c_detach_client(client)) == 0) {
kfree(i2c_get_clientdata(client));
- tasklet_kill(&ds1374_tasklet);
+ destroy_workqueue(ds1374_workqueue);
}
return rc;
}

* * * * *

If it's OK, then Randy can just sign it off and I'll push it to Greg
quickly. If it's not OK for some reason, I'll just wait for a new patch
from Randy.
I've tested the patch. It works fine for me.

Randy V. A tasklet is not suitable for what the ds1374 driver does: neither sleeping
nor mutex operations are allowed in tasklets, and ds1374_set_tlet may do
both.

We can use a workqueue instead, where both sleeping and mutex operations
are allowed.

Acked-by: Randy Vinson <rvinson@xxxxxxxxxx>
Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
---
drivers/i2c/chips/ds1374.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

--- linux-2.6.16-git.orig/drivers/i2c/chips/ds1374.c 2006-03-27 18:25:17.000000000 +0200
+++ linux-2.6.16-git/drivers/i2c/chips/ds1374.c 2006-03-27 18:59:05.000000000 +0200
@@ -27,6 +27,7 @@
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/mutex.h>
+#include <linux/workqueue.h>

#define DS1374_REG_TOD0 0x00
#define DS1374_REG_TOD1 0x01
@@ -139,7 +140,7 @@
return t1;
}

-static void ds1374_set_tlet(ulong arg)
+static void ds1374_set_work(void *arg)
{
ulong t1, t2;
int limit = 10; /* arbitrary retry limit */
@@ -168,17 +169,18 @@

static ulong new_time;

-static DECLARE_TASKLET_DISABLED(ds1374_tasklet, ds1374_set_tlet,
- (ulong) & new_time);
+static struct workqueue_struct *ds1374_workqueue;
+
+static DECLARE_WORK(ds1374_work, ds1374_set_work, &new_time);

int ds1374_set_rtc_time(ulong nowtime)
{
new_time = nowtime;

if (in_interrupt())
- tasklet_schedule(&ds1374_tasklet);
+ queue_work(ds1374_workqueue, &ds1374_work);
else
- ds1374_set_tlet((ulong) & new_time);
+ ds1374_set_work(&new_time);

return 0;
}
@@ -204,6 +206,8 @@
client->adapter = adap;
client->driver = &ds1374_driver;

+ ds1374_workqueue = create_singlethread_workqueue("ds1374");
+
if ((rc = i2c_attach_client(client)) != 0) {
kfree(client);
return rc;
@@ -227,7 +231,7 @@

if ((rc = i2c_detach_client(client)) == 0) {
kfree(i2c_get_clientdata(client));
- tasklet_kill(&ds1374_tasklet);
+ destroy_workqueue(ds1374_workqueue);
}
return rc;
}