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dmaengine: qcom: fix gpi undefined behavior

PATCH Applied Arnd Bergmann 3 participants 3 messages Jan 3, 2021 – Mar 1, 2021

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Arnd Bergmann

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#0 lore raw

PATCH 1/1 dmaengine: qcom: fix gpi undefined behavior

From: Arnd Bergmann <[email protected]>

gcc points out an incorrect error handling loop:

drivers/dma/qcom/gpi.c: In function 'gpi_ch_init':
drivers/dma/qcom/gpi.c:1254:15: error: iteration 2 invokes undefined behavior [-Werror=aggressive-loop-optimizations]
1254 | struct gpii *gpii = gchan->gpii;
| ^~~~
drivers/dma/qcom/gpi.c:1951:2: note: within this loop

 1951 |  for (i = i - 1; i >= 0; i++) {
      |  ^~~

Change the loop to correctly walk backwards through the initialized fields rather than off into the woods.

Fixes 5d0c3533a19f ("dmaengine: qcom: Add GPI dma driver")
Signed-off-by Arnd Bergmann <[email protected]>
---
 drivers/dma/qcom/gpi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/dma/qcom/gpi.c +1 -1
index 8d39d3e24686..9c211104ddbf 100644
@@ -1948,7 +1948,7 @@ static int gpi_ch_init(struct gchan *gchan)
 	return ret;
 
 error_start_chan:
-	for (i = i - 1; i >= 0; i++) {
+	for (i = i - 1; i >= 0; i--) {
 		gpi_stop_chan(&gpii->gchan[i]);
 		gpi_send_cmd(gpii, gchan, GPI_CH_CMD_RESET);
 	}
Signature · 1 line
2.29.2
maintainer Applied
#1 lore raw
Quoted 9 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>

gcc points out an incorrect error handling loop:

drivers/dma/qcom/gpi.c: In function 'gpi_ch_init':
drivers/dma/qcom/gpi.c:1254:15: error: iteration 2 invokes undefined behavior [-Werror=aggressive-loop-optimizations]
1254 | struct gpii *gpii = gchan->gpii;
| ^~~~
drivers/dma/qcom/gpi.c:1951:2: note: within this loop

Quoted 5 lines
 1951 |  for (i = i - 1; i >= 0; i++) {
      |  ^~~

Change the loop to correctly walk backwards through the initialized fields rather than off into the woods.

Applied, thanks

Signature · 1 line
~Vinod
CI Applied
#2 lore raw
In reply to Arnd Bergmann
This patch was applied to qcom/linux.git (refs/heads/for-next):

Hello:

This patch was applied to qcom/linux.git (refs/heads/for-next):

Quoted 9 lines · On Sun, 3 Jan 2021 14:57:29 +0100 you wrote:

From: Arnd Bergmann <[email protected]>

gcc points out an incorrect error handling loop:

drivers/dma/qcom/gpi.c: In function 'gpi_ch_init':
drivers/dma/qcom/gpi.c:1254:15: error: iteration 2 invokes undefined behavior [-Werror=aggressive-loop-optimizations]
1254 | struct gpii *gpii = gchan->gpii;
| ^~~~
drivers/dma/qcom/gpi.c:1951:2: note: within this loop

Quoted 4 lines
 1951 |  for (i = i - 1; i >= 0; i++) {
      |  ^~~

[...]

Here is the summary with links:
- dmaengine: qcom: fix gpi undefined behavior

    https://git.kernel.org/qcom/c/0bd1bf86ab79

You are awesome, thank you!
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