i2c: make sure i2c_master_send/recv return negative error codes
Subsystems (2)
PATCH 1/1 i2c: make sure i2c_master_send/recv return negative error codes
There is theoretical possibility that i2c_master_send() and i2c_master_recv() may return non-negative result on error: we pass return values from i2c_xfer() unmodified to the caller, unless we transferred exactly 1 message. Let's ensure we always return negative on error.
--- drivers/i2c/i2c-core.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
drivers/i2c/i2c-core.c +8 -2
@@ -2835,7 +2835,10 @@ int i2c_master_send(const struct i2c_client *client, const void *buf, int count)* If everything went ok (i.e. 1 msg transmitted), return #bytes * transmitted, else error code. */ -return (ret ==1 ) ? count : ret; +if (likely (ret ==1 )) +return count; + +return ret <0 ? ret : -EIO ; }EXPORT_SYMBOL (i2c_master_send);
@@ -2865,7 +2868,10 @@ int i2c_master_recv(const struct i2c_client *client, void *buf, int count)* If everything went ok (i.e. 1 msg received), return #bytes received, * else error code. */ -return (ret ==1 ) ? count : ret; +if (likely (ret ==1 )) +return count; + +return ret <0 ? ret : -EIO ; }EXPORT_SYMBOL (i2c_master_recv);
Signature · 5 lines
2.12.2.564.g063fe858b8-goog -- Dmitry
Hi Dmirty,
Quoted 29 lines · Dmitry Torokhov
There is theoretical possibility that
i2c_master_send()andi2c_master_recv()may return non-negative result on error: we pass return values fromi2c_xfer()unmodified to the caller, unless we transferred exactly 1 message. Let's ensure we always return negative on error.Signed-off-by Dmitry Torokhov <[email protected]>--- drivers/i2c/i2c-core.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)drivers/i2c/i2c-core.c +4
-1@@ -2835,7 +2835,10 @@ int i2c_master_send(const struct i2c_client *client, const void *buf, int count)* If everything went ok (i.e. 1 msg transmitted), return #bytes * transmitted, else error code. */ -return (ret ==1 ) ? count : ret; +if (likely (ret ==1 )) +return count; + +return ret <0 ? ret : -EIO ; }EXPORT_SYMBOL (i2c_master_send);@@ -2865,7 +2868,10 @@ int i2c_master_recv(const struct i2c_client *client, void *buf, int count)* If everything went ok (i.e. 1 msg received), return #bytes received,
drivers/i2c/i2c-core.c int i2c_master_recv(const struct i2c_client *client, void *buf, int count) · line 2877
Quoted 10 lines
drivers/i2c/i2c-core.c +4
-1* else error code. */ -return (ret ==1 ) ? count : ret; +if (likely (ret ==1 )) +return count; + +return ret <0 ? ret : -EIO ; }EXPORT_SYMBOL (i2c_master_recv);
I'm not convinced.
Firstly, that would be a device driver bug, and I can't see how silently working around it here helps. If a driver is broken, it should be fixed. So I would expect a log message.
Secondly, I believe i2c_master_send() and i2c_master_recv() should be able to trust the return value of i2c_transfer(), which in turn should be able to trust the return value of __i2c_transfer(). If you really want to check the value returned by i2c_algo->master_xfer() for validity, this should be done in __i2c_transfer(). But then again, I find it hard to justify the run-time overhead for working drivers, so maybe it should only be done if CONFIG_I2C_DEBUG_BUS is enabled.
Signature · 10 lines
Jean Delvare SUSE L3 Support -- Jean Delvare SUSE L3 Support -- Jean Delvare SUSE L3 Support