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SubjectRe: [PATCH V3 1/2] bdisp: Fix a possible sleep-in-atomic bug in bdisp_hw_reset
Date
Hi,


It's almost good!

You have to fix these checkpatch Warning/Check:

WARNING: Block comments use a trailing */ on a separate line
#36: FILE: drivers/media/platform/sti/bdisp/bdisp-hw.c:383:
+     * needing any delays */

CHECK: Alignment should match open parenthesis
#38: FILE: drivers/media/platform/sti/bdisp/bdisp-hw.c:385:
+    if (readl_poll_timeout_atomic(bdisp->regs + BLT_STA1, tmp,
+        (tmp & BLT_STA1_IDLE), POLL_RST_DELAY_MS,


From kernel documentation in the "Posting patches" chapter:

"You should always run patches through scripts/checkpatch.pl and address
the complaints it comes up with."

And, please use the --strict option

Thanks for your understanding.

BR

Fabien

On 19/12/17 14:57, Jia-Ju Bai wrote:
> The driver may sleep under a spinlock.
> The function call path is:
> bdisp_device_run (acquire the spinlock)
> bdisp_hw_reset
> msleep --> may sleep
>
> To fix it, readl_poll_timeout_atomic is used to replace msleep.
>
> This bug is found by my static analysis tool(DSAC) and
> checked by my code review.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> ---
> drivers/media/platform/sti/bdisp/bdisp-hw.c | 23 ++++++++++++-----------
> 1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/media/platform/sti/bdisp/bdisp-hw.c b/drivers/media/platform/sti/bdisp/bdisp-hw.c
> index b7892f3..b63d9c9 100644
> --- a/drivers/media/platform/sti/bdisp/bdisp-hw.c
> +++ b/drivers/media/platform/sti/bdisp/bdisp-hw.c
> @@ -4,7 +4,7 @@
> * License terms: GNU General Public License (GPL), version 2
> */
>
> -#include <linux/delay.h>
> +#include <linux/iopoll.h>
>
> #include "bdisp.h"
> #include "bdisp-filter.h"
> @@ -15,7 +15,7 @@
>
> /* Reset & boot poll config */
> #define POLL_RST_MAX 50
> -#define POLL_RST_DELAY_MS 20
> +#define POLL_RST_DELAY_US 20000
>
> enum bdisp_target_plan {
> BDISP_RGB,
> @@ -366,7 +366,7 @@ struct bdisp_filter_addr {
> */
> int bdisp_hw_reset(struct bdisp_dev *bdisp)
> {
> - unsigned int i;
> + u32 tmp;
>
> dev_dbg(bdisp->dev, "%s\n", __func__);
>
> @@ -378,16 +378,17 @@ int bdisp_hw_reset(struct bdisp_dev *bdisp)
> bdisp->regs + BLT_CTL);
> writel(0, bdisp->regs + BLT_CTL);
>
> - /* Wait for reset done */
> - for (i = 0; i < POLL_RST_MAX; i++) {
> - if (readl(bdisp->regs + BLT_STA1) & BLT_STA1_IDLE)
> - break;
> - msleep(POLL_RST_DELAY_MS);
> - }
> - if (i == POLL_RST_MAX)
> + /* Wait for reset done.
> + * Despite the large timeout, most of the time the reset happens without
> + * needing any delays */

shall be

+ * needing any delays

+ */

> + if (readl_poll_timeout_atomic(bdisp->regs + BLT_STA1, tmp,
> + (tmp & BLT_STA1_IDLE), POLL_RST_DELAY_US,
> + POLL_RST_DELAY_US * POLL_RST_MAX)) {

shall be:

+ if (readl_poll_timeout_atomic(bdisp->regs + BLT_STA1, tmp,
+ tmp & BLT_STA1_IDLE, POLL_RST_DELAY_US,
+ POLL_RST_DELAY_US * POLL_RST_MAX)) {

> dev_err(bdisp->dev, "Reset timeout\n");
> + return -EAGAIN;
> + }
>
> - return (i == POLL_RST_MAX) ? -EAGAIN : 0;
> + return 0;
> }
>
> /**
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