Hi
On Thursday, May 19, 2011 02:35:08 PM Pavel Machek wrote:
> > you're potentially doing with this:
> In some other mail, you said "just add the locking". Pavel H.
> actually produced patch doing so...
yes, that was the original version of the patch. while I agree with Marek on
locks not being the right way, I was going send a cleaner version of the
original locking patch today (locking in probe is not really necessary), you
just beat me to it.
Pavel Herrmann
From 5782df40e6c343b6dc9ff5ca008c1ee8b50cad51 Mon Sep 17 00:00:00 2001
From: Pavel Herrmann <morpheus.i...@gmail.com>
Date: Mon, 16 May 2011 14:18:18 +0200
Subject: [PATCH 1/2] Fix NULL pointer exception in max1111
Signed-off-by: Pavel Herrmann <morpheus.i...@gmail.com>
---
drivers/hwmon/max1111.c | 15 +++++++++++++++
1 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/drivers/hwmon/max1111.c b/drivers/hwmon/max1111.c
index 12a54aa..c748fa3 100644
--- a/drivers/hwmon/max1111.c
+++ b/drivers/hwmon/max1111.c
@@ -40,6 +40,7 @@ struct max1111_data {
struct spi_transfer xfer[2];
uint8_t *tx_buf;
uint8_t *rx_buf;
+ struct mutex msg_lock_mutex;
};
static int max1111_read(struct device *dev, int channel)
@@ -52,7 +53,14 @@ static int max1111_read(struct device *dev, int channel)
MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
+ /* spi_sync requires data not to be freed before function returns
+ * for static data, any access is dangerous, use locks
+ */
+ mutex_lock(&data->msg_lock_mutex);
+
err = spi_sync(data->spi, &data->msg);
+
+ mutex_unlock(&data->msg_lock_mutex);
if (err < 0) {
dev_err(dev, "spi_sync failed with %d\n", err);
return err;
@@ -138,6 +146,8 @@ static int setup_transfer(struct max1111_data *data)
return -ENOMEM;
}
+ mutex_lock(&data->msg_lock_mutex);
+
m = &data->msg;
x = &data->xfer[0];
@@ -152,6 +162,8 @@ static int setup_transfer(struct max1111_data *data)
x->len = 2;
spi_message_add_tail(x, m);
+ mutex_unlock(&data->msg_lock_mutex);
+
return 0;
}
@@ -172,6 +184,8 @@ static int __devinit max1111_probe(struct spi_device *spi)
return -ENOMEM;
}
+ mutex_init(&data->msg_lock_mutex);
+
err = setup_transfer(data);
if (err)
goto err_free_data;
@@ -213,6 +227,7 @@ static int __devexit max1111_remove(struct spi_device *spi)
hwmon_device_unregister(data->hwmon_dev);
sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
+ mutex_destroy(data->msg_lock_mutex);
kfree(data->rx_buf);
kfree(data->tx_buf);
kfree(data);
--
1.7.5.rc1
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