lkml.org 
[lkml]   [2003]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [RFC][2.5] list_for_each_safe not so safe (was Re: OOPS w83781d during rmmod (2.5.70-bk1[1234]))
* Martin Schlemmer <azarah@gentoo.org> [2003-06-12 08:57:02 +0200]:
> On Tue, 2003-06-10 at 07:41, Mark M. Hoffman wrote:
> > * Martin Schlemmer <azarah@gentoo.org> [2003-06-09 07:34:30 +0200]:
> > >
> > > Anyhow, Only change I have made to the w83781d driver, is one line
> > > (just tell it to that if the chip id is 0x72, its also of type
> > > w83726HF), but now (2.5.70-bk1[123]) it segfaults for me on rmmod, where
> > > it did not with 2.5.68 kernels when I still had the other board. I will
> > > attach a oops tomorrow or such when I get home.
> >
> > I reproduced the segfault here. It looks like i2c_del_driver() tries
> > to call w83781d_detach_client() more than once now, partly because of
> > the safe list fix in 2.5.70-bk11. But that function should only be
> > called for the "primary" client, not the subclients.
> >
> > The quick/ugly patch below fixes the symptom, but maybe not the disease.
> > There might be more fundamental brokenness in the whole subclient scheme.
> > I'll keep looking when I get the chance.
> >
> > <broken patch ommitted>
>
> Nope, this do not fix it.
>
> The problem is actually at the i2c driver side. From
> drivers/i2c/i2c-core.c in i2c_del_driver(), we have:
<cut>

To recap: list_for_each_safe() is not safe for deleting other than
the current "item". But I disagree with you Martin because I think
the usage in i2c_del_driver is ok as is; and that w83781d.c should
change...

My first patch was naive; the patch below solves the problem by
letting w83781d_detach_client remove the three clients (1 * primary
+ 2 * subclients) independently. It's a noisy patch because I had
to change the way the subclients were kmalloc'ed - sorry. The meat
is around line 1422. This patch works for me... comments?

Regards,

--- linux-2.5.70-bk14/drivers/i2c/chips/w83781d.c 2003-06-10 00:49:19.000000000 -0400
+++ linux-2.5.70/drivers/i2c/chips/w83781d.c 2003-06-12 22:24:47.000000000 -0400
@@ -299,8 +299,8 @@
char valid; /* !=0 if following fields are valid */
unsigned long last_updated; /* In jiffies */

- struct i2c_client *lm75; /* for secondary I2C addresses */
- /* pointer to array of 2 subclients */
+ struct i2c_client *lm75[2]; /* for secondary I2C addresses */
+ /* array of 2 pointers to subclients */

u8 in[9]; /* Register value - 8 & 9 for 782D only */
u8 in_max[9]; /* Register value - 8 & 9 for 782D only */
@@ -1043,12 +1043,12 @@
const char *client_name;
struct w83781d_data *data = i2c_get_clientdata(new_client);

- if (!(data->lm75 = kmalloc(2 * sizeof (struct i2c_client),
- GFP_KERNEL))) {
+ data->lm75[0] = kmalloc(sizeof(struct i2c_client), GFP_KERNEL);
+ if (!(data->lm75[0])) {
err = -ENOMEM;
goto ERROR_SC_0;
}
- memset(data->lm75, 0x00, 2 * sizeof (struct i2c_client));
+ memset(data->lm75[0], 0x00, sizeof (struct i2c_client));

id = i2c_adapter_id(adapter);

@@ -1066,25 +1066,33 @@
w83781d_write_value(new_client, W83781D_REG_I2C_SUBADDR,
(force_subclients[2] & 0x07) |
((force_subclients[3] & 0x07) << 4));
- data->lm75[0].addr = force_subclients[2];
+ data->lm75[0]->addr = force_subclients[2];
} else {
val1 = w83781d_read_value(new_client, W83781D_REG_I2C_SUBADDR);
- data->lm75[0].addr = 0x48 + (val1 & 0x07);
+ data->lm75[0]->addr = 0x48 + (val1 & 0x07);
}

if (kind != w83783s) {
+
+ data->lm75[1] = kmalloc(sizeof(struct i2c_client), GFP_KERNEL);
+ if (!(data->lm75[1])) {
+ err = -ENOMEM;
+ goto ERROR_SC_1;
+ }
+ memset(data->lm75[1], 0x0, sizeof(struct i2c_client));
+
if (force_subclients[0] == id &&
force_subclients[1] == address) {
- data->lm75[1].addr = force_subclients[3];
+ data->lm75[1]->addr = force_subclients[3];
} else {
- data->lm75[1].addr = 0x48 + ((val1 >> 4) & 0x07);
+ data->lm75[1]->addr = 0x48 + ((val1 >> 4) & 0x07);
}
- if (data->lm75[0].addr == data->lm75[1].addr) {
+ if (data->lm75[0]->addr == data->lm75[1]->addr) {
dev_err(&new_client->dev,
"Duplicate addresses 0x%x for subclients.\n",
- data->lm75[0].addr);
+ data->lm75[0]->addr);
err = -EBUSY;
- goto ERROR_SC_1;
+ goto ERROR_SC_2;
}
}

@@ -1103,19 +1111,19 @@

for (i = 0; i <= 1; i++) {
/* store all data in w83781d */
- i2c_set_clientdata(&data->lm75[i], NULL);
- data->lm75[i].adapter = adapter;
- data->lm75[i].driver = &w83781d_driver;
- data->lm75[i].flags = 0;
- strlcpy(data->lm75[i].dev.name, client_name,
+ i2c_set_clientdata(data->lm75[i], NULL);
+ data->lm75[i]->adapter = adapter;
+ data->lm75[i]->driver = &w83781d_driver;
+ data->lm75[i]->flags = 0;
+ strlcpy(data->lm75[i]->dev.name, client_name,
DEVICE_NAME_SIZE);
- if ((err = i2c_attach_client(&(data->lm75[i])))) {
+ if ((err = i2c_attach_client(data->lm75[i]))) {
dev_err(&new_client->dev, "Subclient %d "
"registration at address 0x%x "
- "failed.\n", i, data->lm75[i].addr);
+ "failed.\n", i, data->lm75[i]->addr);
if (i == 1)
- goto ERROR_SC_2;
- goto ERROR_SC_1;
+ goto ERROR_SC_3;
+ goto ERROR_SC_2;
}
if (kind == w83783s)
break;
@@ -1124,10 +1132,14 @@
return 0;

/* Undo inits in case of errors */
+ERROR_SC_3:
+ i2c_detach_client(data->lm75[0]);
ERROR_SC_2:
- i2c_detach_client(&(data->lm75[0]));
+ if (NULL != data->lm75[1])
+ kfree(data->lm75[1]);
ERROR_SC_1:
- kfree(data->lm75);
+ if (NULL != data->lm75[0])
+ kfree(data->lm75[0]);
ERROR_SC_0:
return err;
}
@@ -1326,7 +1338,8 @@
kind, new_client)))
goto ERROR3;
} else {
- data->lm75 = NULL;
+ data->lm75[0] = NULL;
+ data->lm75[1] = NULL;
}

device_create_file_in(new_client, 0);
@@ -1409,20 +1422,11 @@
static int
w83781d_detach_client(struct i2c_client *client)
{
- struct w83781d_data *data = i2c_get_clientdata(client);
int err;

- /* release ISA region or I2C subclients first */
- if (i2c_is_isa_client(client)) {
+ if (i2c_is_isa_client(client))
release_region(client->addr, W83781D_EXTENT);
- } else {
- i2c_detach_client(&data->lm75[0]);
- if (data->type != w83783s)
- i2c_detach_client(&data->lm75[1]);
- kfree(data->lm75);
- }

- /* now it's safe to scrap the rest */
if ((err = i2c_detach_client(client))) {
dev_err(&client->dev,
"Client deregistration failed, client not detached.\n");
@@ -1484,7 +1488,7 @@
res = i2c_smbus_read_byte_data(client, reg & 0xff);
} else {
/* switch to subclient */
- cl = &data->lm75[bank - 1];
+ cl = data->lm75[bank - 1];
/* convert from ISA to LM75 I2C addresses */
switch (reg & 0xff) {
case 0x50: /* TEMP */
@@ -1555,7 +1559,7 @@
value & 0xff);
} else {
/* switch to subclient */
- cl = &data->lm75[bank - 1];
+ cl = data->lm75[bank - 1];
/* convert from ISA to LM75 I2C addresses */
switch (reg & 0xff) {
case 0x52: /* CONFIG */

--
Mark M. Hoffman
mhoffman@lightlink.com

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:36    [W:0.067 / U:2.644 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site