| Message ID | 20170401175435.GA12354@dtor-ws |
|---|---|
| State | New |
| Headers | show |
Hi Dmirty, On Sat, 1 Apr 2017 10:54:35 -0700, Dmitry Torokhov wrote: > 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. > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > --- > drivers/i2c/i2c-core.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 6efeba42d10b..34b0482333f4 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -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); > 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.
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 6efeba42d10b..34b0482333f4 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -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);
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. Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- drivers/i2c/i2c-core.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)