2021-08-09 04:09:47

by Miaoqing Pan

Subject: [PATCH] ath9k: fix sleeping in atomic context

The problem is that gpio_free() can sleep and the cfg_soc() can be
called with spinlocks held. One problematic call tree is:

--> ath_reset_internal() takes &sc->sc_pcu_lock spin lock
--> ath9k_hw_reset()
--> ath9k_hw_gpio_request_in()
--> ath9k_hw_gpio_request()
--> ath9k_hw_gpio_cfg_soc()

Remove gpio_free(), use error message instead, so we should make sure
there is no GPIO conflict.

Also remove ath9k_hw_gpio_free() from ath9k_hw_apply_gpio_override(),
as gpio_mask will never be set for SOC chips.

Signed-off-by: Miaoqing Pan <[email protected]>
---
drivers/net/wireless/ath/ath9k/hw.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 2ca3b86..172081f 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1621,7 +1621,6 @@ static void ath9k_hw_apply_gpio_override(struct ath_hw *ah)
ath9k_hw_gpio_request_out(ah, i, NULL,
AR_GPIO_OUTPUT_MUX_AS_OUTPUT);
ath9k_hw_set_gpio(ah, i, !!(ah->gpio_val & BIT(i)));
- ath9k_hw_gpio_free(ah, i);
}
}

@@ -2728,14 +2727,17 @@ static void ath9k_hw_gpio_cfg_output_mux(struct ath_hw *ah, u32 gpio, u32 type)
static void ath9k_hw_gpio_cfg_soc(struct ath_hw *ah, u32 gpio, bool out,
const char *label)
{
+ int err;
+
if (ah->caps.gpio_requested & BIT(gpio))
return;

- /* may be requested by BSP, free anyway */
- gpio_free(gpio);
-
- if (gpio_request_one(gpio, out ? GPIOF_OUT_INIT_LOW : GPIOF_IN, label))
+ err = gpio_request_one(gpio, out ? GPIOF_OUT_INIT_LOW : GPIOF_IN, label);
+ if (err) {
+ ath_err(ath9k_hw_common(ah), "request GPIO%d failed:%d\n",
+ gpio, err);
return;
+ }

ah->caps.gpio_requested |= BIT(gpio);
}
--
2.7.4

2021-08-29 07:14:10

by Kalle Valo

Subject: Re: [PATCH] ath9k: fix sleeping in atomic context

Miaoqing Pan <[email protected]> wrote:

> The problem is that gpio_free() can sleep and the cfg_soc() can be
> called with spinlocks held. One problematic call tree is:
>
> --> ath_reset_internal() takes &sc->sc_pcu_lock spin lock
> --> ath9k_hw_reset()
> --> ath9k_hw_gpio_request_in()
> --> ath9k_hw_gpio_request()
> --> ath9k_hw_gpio_cfg_soc()
>
> Remove gpio_free(), use error message instead, so we should make sure
> there is no GPIO conflict.
>
> Also remove ath9k_hw_gpio_free() from ath9k_hw_apply_gpio_override(),
> as gpio_mask will never be set for SOC chips.
>
> Signed-off-by: Miaoqing Pan <[email protected]>
> Signed-off-by: Kalle Valo <[email protected]>

Patch applied to ath-next branch of ath.git, thanks.

7c48662b9d56 ath9k: fix sleeping in atomic context

--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches