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From: Marek Szyprowski <m.szyprowski@samsung.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Russell King" <linux@armlinux.org.uk>,
	"Stephen Boyd" <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org, kernel@pengutronix.de,
	Michael Turquette <mturquette@baylibre.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Alexandru Ardelean <aardelean@deviqon.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH v9 2/4] clk: generalize devm_clk_get() a bit
Date: Mon, 20 Jun 2022 17:26:12 +0200	[thread overview]
Message-ID: <0cdc7588-4dc3-266f-aa37-86bf5996497f@samsung.com> (raw)
In-Reply-To: <20220520075737.758761-3-u.kleine-koenig@pengutronix.de>

Hi Uwe,

On 20.05.2022 09:57, Uwe Kleine-König wrote:
> Allow to add an exit hook to devm managed clocks. Also use
> clk_get_optional() in devm_clk_get_optional instead of open coding it.
> The generalisation will be used in the next commit to add some more
> devm_clk helpers.
>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Alexandru Ardelean <aardelean@deviqon.com>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

This patch landed in linux next-20220620 as commit abae8e57e49a ("clk: 
generalize devm_clk_get() a bit"). Unfortunately it has ugly issue, see 
my comment in the code below.

> ---
>   drivers/clk/clk-devres.c | 66 +++++++++++++++++++++++++++++-----------
>   1 file changed, 49 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c
> index f9d5b7334341..c822f4ef1584 100644
> --- a/drivers/clk/clk-devres.c
> +++ b/drivers/clk/clk-devres.c
> @@ -4,39 +4,71 @@
>   #include <linux/export.h>
>   #include <linux/gfp.h>
>   
> +struct devm_clk_state {
> +	struct clk *clk;
> +	void (*exit)(struct clk *clk);
> +};
> +
>   static void devm_clk_release(struct device *dev, void *res)
>   {
> -	clk_put(*(struct clk **)res);
> +	struct devm_clk_state *state = *(struct devm_clk_state **)res;

This should be:

struct devm_clk_state *state = res;

otherwise it nukes badly during cleanup:

8<--- cut here ---
Unable to handle kernel paging request at virtual address c254f810
[c254f810] *pgd=4241141e(bad)
Internal error: Oops: 8000000d [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.19.0-rc1-00002-gabae8e57e49a #5239
Hardware name: Samsung Exynos (Flattened Device Tree)
PC is at 0xc254f810
LR is at devm_clk_release+0x1c/0x28
pc : [<c254f810>]    lr : [<c05c93f4>]    psr: a0000053
...
Flags: NzCv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment none
Control: 10c5387d  Table: 4000404a  DAC: 00000051
...
Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
Stack: (0xf0845dd0 to 0xf0846000)
...
  devm_clk_release from release_nodes+0x5c/0x80
  release_nodes from devres_release_all+0x7c/0xc0
  devres_release_all from device_unbind_cleanup+0xc/0x60
  device_unbind_cleanup from really_probe+0x150/0x404
  really_probe from __driver_probe_device+0xa0/0x208
  __driver_probe_device from driver_probe_device+0x34/0xc4
  driver_probe_device from __driver_attach+0xf0/0x1e4
  __driver_attach from bus_for_each_dev+0x70/0xb0
  bus_for_each_dev from bus_add_driver+0x174/0x218
  bus_add_driver from driver_register+0x88/0x11c
  driver_register from do_one_initcall+0x64/0x380
  do_one_initcall from kernel_init_freeable+0x1c0/0x224
  kernel_init_freeable from kernel_init+0x18/0x12c
  kernel_init from ret_from_fork+0x14/0x2c
Exception stack(0xf0845fb0 to 0xf0845ff8)
...
---[ end trace 0000000000000000 ]---


> +
> +	if (state->exit)
> +		state->exit(state->clk);
> +
> +	clk_put(state->clk);
>   }
>   
> -struct clk *devm_clk_get(struct device *dev, const char *id)
> +static struct clk *__devm_clk_get(struct device *dev, const char *id,
> +				  struct clk *(*get)(struct device *dev, const char *id),
> +				  int (*init)(struct clk *clk),
> +				  void (*exit)(struct clk *clk))
>   {
> -	struct clk **ptr, *clk;
> +	struct devm_clk_state *state;
> +	struct clk *clk;
> +	int ret;
>   
> -	ptr = devres_alloc(devm_clk_release, sizeof(*ptr), GFP_KERNEL);
> -	if (!ptr)
> +	state = devres_alloc(devm_clk_release, sizeof(*state), GFP_KERNEL);
> +	if (!state)
>   		return ERR_PTR(-ENOMEM);
>   
> -	clk = clk_get(dev, id);
> -	if (!IS_ERR(clk)) {
> -		*ptr = clk;
> -		devres_add(dev, ptr);
> -	} else {
> -		devres_free(ptr);
> +	clk = get(dev, id);
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		goto err_clk_get;
>   	}
>   
> +	if (init) {
> +		ret = init(clk);
> +		if (ret)
> +			goto err_clk_init;
> +	}
> +
> +	state->clk = clk;
> +	state->exit = exit;
> +
> +	devres_add(dev, state);
> +
>   	return clk;
> +
> +err_clk_init:
> +
> +	clk_put(clk);
> +err_clk_get:
> +
> +	devres_free(state);
> +	return ERR_PTR(ret);
> +}
> +
> +struct clk *devm_clk_get(struct device *dev, const char *id)
> +{
> +	return __devm_clk_get(dev, id, clk_get, NULL, NULL);
>   }
>   EXPORT_SYMBOL(devm_clk_get);
>   
>   struct clk *devm_clk_get_optional(struct device *dev, const char *id)
>   {
> -	struct clk *clk = devm_clk_get(dev, id);
> -
> -	if (clk == ERR_PTR(-ENOENT))
> -		return NULL;
> -
> -	return clk;
> +	return __devm_clk_get(dev, id, clk_get_optional, NULL, NULL);
>   }
>   EXPORT_SYMBOL(devm_clk_get_optional);
>   

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland


  parent reply	other threads:[~2022-06-20 15:27 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20  7:57 [PATCH v9 0/4] clk: provide new devm helpers for prepared and enabled clocks Uwe Kleine-König
2022-05-20  7:57 ` Uwe Kleine-König
2022-05-20  7:57 ` [PATCH v9 1/4] clk: Improve documentation for devm_clk_get() and its optional variant Uwe Kleine-König
2022-06-07 11:46   ` Russell King (Oracle)
2022-06-16  2:35   ` Stephen Boyd
2022-05-20  7:57 ` [PATCH v9 2/4] clk: generalize devm_clk_get() a bit Uwe Kleine-König
2022-06-16  2:35   ` Stephen Boyd
     [not found]   ` <CGME20220620152612eucas1p2bd95bcec491a02c486d0a5f6b97864cd@eucas1p2.samsung.com>
2022-06-20 15:26     ` Marek Szyprowski [this message]
2022-06-20 17:18       ` [PATCH] clk: Fix pointer casting to prevent oops in devm_clk_release() Uwe Kleine-König
2022-06-21  6:25         ` Marek Szyprowski
2022-06-21  9:52           ` Uwe Kleine-König
2022-06-22 17:22         ` Uwe Kleine-König
2022-06-22 23:11         ` Stephen Boyd
2022-05-20  7:57 ` [PATCH v9 3/4] clk: Provide new devm_clk helpers for prepared and enabled clocks Uwe Kleine-König
2022-06-16  2:37   ` Stephen Boyd
2022-05-20  7:57 ` [PATCH v9 4/4] clk: meson: axg-audio: Don't duplicate devm_clk_get_enabled() Uwe Kleine-König
2022-05-20  7:57   ` Uwe Kleine-König
2022-06-16  2:37   ` Stephen Boyd
2022-06-16  2:37     ` Stephen Boyd
2022-06-07 11:08 ` [PATCH v9 0/4] clk: provide new devm helpers for prepared and enabled clocks Uwe Kleine-König
2022-06-07 11:08   ` Uwe Kleine-König
2022-06-07 11:42   ` Russell King (Oracle)
2022-06-07 11:42     ` Russell King (Oracle)

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