| Message ID | 20190312124442.10098-1-wsa+renesas@sang-engineering.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
| Series | [v2] i2c: add extra check to safe DMA buffer helper | expand |
On Tue, Mar 12, 2019 at 8:44 PM Wolfram Sang <wsa+renesas@sang-engineering.com> wrote: > > Make sure we report 'no buffer' for 0-length messages. This can only > happen if threshold is set to 0 which is kind of bogus but we should > still handle this situation. Update the docs and add a debug message > to educate callers of this function. > > Reported-by: Hsin-Yi Wang <hsinyi@chromium.org> > Fixes: e94bc5d18be0 ("i2c: add helpers to ease DMA handling") > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Thanks! Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org> > --- > > Changes since v1: > * add debug print > * update kernel doc > * update commit message > > drivers/i2c/i2c-core-base.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c > index cb6c5cb0df0b..986e56cee44b 100644 > --- a/drivers/i2c/i2c-core-base.c > +++ b/drivers/i2c/i2c-core-base.c > @@ -2258,7 +2258,8 @@ EXPORT_SYMBOL(i2c_put_adapter); > /** > * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg > * @msg: the message to be checked > - * @threshold: the minimum number of bytes for which using DMA makes sense > + * @threshold: the minimum number of bytes for which using DMA makes sense. > + * Should at least be 1. > * > * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO. > * Or a valid pointer to be used with DMA. After use, release it by > @@ -2268,7 +2269,11 @@ EXPORT_SYMBOL(i2c_put_adapter); > */ > u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold) > { > - if (msg->len < threshold) > + /* also skip 0-length msgs for bogus thresholds of 0 */ > + if (!threshold) > + pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n", > + msg->addr); > + if (msg->len < threshold || msg->len == 0) > return NULL; > > if (msg->flags & I2C_M_DMA_SAFE) > -- > 2.11.0 >
On Tue, Mar 12, 2019 at 01:44:42PM +0100, Wolfram Sang wrote: > Make sure we report 'no buffer' for 0-length messages. This can only > happen if threshold is set to 0 which is kind of bogus but we should > still handle this situation. Update the docs and add a debug message > to educate callers of this function. > > Reported-by: Hsin-Yi Wang <hsinyi@chromium.org> > Fixes: e94bc5d18be0 ("i2c: add helpers to ease DMA handling") > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Fixed a whitespace issue and applied to for-current, thanks!
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index cb6c5cb0df0b..986e56cee44b 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -2258,7 +2258,8 @@ EXPORT_SYMBOL(i2c_put_adapter); /** * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg * @msg: the message to be checked - * @threshold: the minimum number of bytes for which using DMA makes sense + * @threshold: the minimum number of bytes for which using DMA makes sense. + * Should at least be 1. * * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO. * Or a valid pointer to be used with DMA. After use, release it by @@ -2268,7 +2269,11 @@ EXPORT_SYMBOL(i2c_put_adapter); */ u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold) { - if (msg->len < threshold) + /* also skip 0-length msgs for bogus thresholds of 0 */ + if (!threshold) + pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n", + msg->addr); + if (msg->len < threshold || msg->len == 0) return NULL; if (msg->flags & I2C_M_DMA_SAFE)
Make sure we report 'no buffer' for 0-length messages. This can only happen if threshold is set to 0 which is kind of bogus but we should still handle this situation. Update the docs and add a debug message to educate callers of this function. Reported-by: Hsin-Yi Wang <hsinyi@chromium.org> Fixes: e94bc5d18be0 ("i2c: add helpers to ease DMA handling") Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- Changes since v1: * add debug print * update kernel doc * update commit message drivers/i2c/i2c-core-base.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)