diff options
| author | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2019-03-12 13:44:42 +0100 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2019-03-13 18:03:26 +0100 |
| commit | bf263c35b2ebe7f1674205f6b36487250299b5a7 (patch) | |
| tree | d281179a1dfafd96a655cd4234e1238179973113 /drivers/i2c/i2c-core-base.c | |
| parent | c86da50cfd840edf223a242580913692acddbcf6 (diff) | |
| download | linux-bf263c35b2ebe7f1674205f6b36487250299b5a7.tar.bz2 | |
i2c: add extra check to safe DMA buffer helper
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>
Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/i2c-core-base.c')
| -rw-r--r-- | drivers/i2c/i2c-core-base.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index cb6c5cb0df0b..38af18645133 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) |