[+ Wolfram]
Am 2022-05-05 16:51, schrieb Nathan Chancellor:
On Thu, Apr 07, 2022 at 05:08:28PM +0200, Michael Walle wrote:
The supplied buffer might be on the stack and we get the following
error
message:
[ 3.312058] at91_i2c e0070600.i2c: rejecting DMA map of vmalloc
memory
Use i2c_{get,put}_dma_safe_msg_buf() to get a DMA-able memory region
if
necessary.
Fixes: 60937b2cdbf9 ("i2c: at91: add dma support")
Signed-off-by: Michael Walle <michael@xxxxxxxx>
Reviewed-by: Codrin Ciubotariu <codrin.ciubotariu@xxxxxxxxxxxxx>
---
changes since v1:
- remove extra empty line
- add fixes tag as suggested by Codrin
drivers/i2c/busses/i2c-at91-master.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/i2c/busses/i2c-at91-master.c
b/drivers/i2c/busses/i2c-at91-master.c
index b0eae94909f4..5eca3b3bb609 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -656,6 +656,7 @@ static int at91_twi_xfer(struct i2c_adapter *adap,
struct i2c_msg *msg, int num)
unsigned int_addr_flag = 0;
struct i2c_msg *m_start = msg;
bool is_read;
+ u8 *dma_buf;
dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
@@ -703,7 +704,17 @@ static int at91_twi_xfer(struct i2c_adapter
*adap, struct i2c_msg *msg, int num)
dev->msg = m_start;
dev->recv_len_abort = false;
+ if (dev->use_dma) {
+ dma_buf = i2c_get_dma_safe_msg_buf(m_start, 1);
+ if (!dma_buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ dev->buf = dma_buf;
+ }
+
ret = at91_do_twi_transfer(dev);
+ i2c_put_dma_safe_msg_buf(dma_buf, m_start, !ret);
ret = (ret < 0) ? ret : num;
out:
--
2.30.2
This change as commit 03fbb903c8bf ("i2c: at91: use dma safe buffers")
causes the following clang warning:
Ugh..
drivers/i2c/busses/i2c-at91-master.c:707:6: error: variable 'dma_buf'
is used uninitialized whenever 'if' condition is false
[-Werror,-Wsometimes-uninitialized]
if (dev->use_dma) {
^~~~~~~~~~~~
drivers/i2c/busses/i2c-at91-master.c:717:27: note: uninitialized use
occurs here
i2c_put_dma_safe_msg_buf(dma_buf, m_start, !ret);
^~~~~~~
drivers/i2c/busses/i2c-at91-master.c:707:2: note: remove the 'if' if
its condition is always true
if (dev->use_dma) {
^~~~~~~~~~~~~~~~~~
drivers/i2c/busses/i2c-at91-master.c:659:13: note: initialize the
variable 'dma_buf' to silence this warning
u8 *dma_buf;
^
= NULL
1 error generated.
Should this variable be initialized or should the call to
i2c_put_dma_safe_msg_buf() be moved into the if statement?
Initializing dma_buf with NULL should to the trick because
i2c_put_dma_safe_msg_buf() is handling NULL gracefully. No
need for an extra "if (dma_buf)".
Will you take care or should I send a patch?
-michael
