Re: [PATCH v2] clkdev: Always allocate a struct clk and call __clk_get() w/ CCF

[Tomeu Vizoso <tomeu.vizoso@collabora.com>]

On 02/06/2015 02:40 AM, Stephen Boyd wrote:
> of_clk_get_by_clkspec() returns a struct clk pointer but it
> doesn't create a new handle for the consumers when we're using
> the common clock framework. Instead it just returns whatever the
> clk provider hands out. When the consumers go to call clk_put()
> we get an Oops.
> 
> Unable to handle kernel paging request at virtual address 00200200
> pgd = c0004000
> [00200200] *pgd=00000000
> Internal error: Oops: 805 [#1] PREEMPT SMP ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.19.0-rc1-00104-ga251361a-dirty #992
> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> task: ee00b000 ti: ee088000 task.ti: ee088000
> PC is at __clk_put+0x24/0xd0
> LR is at clk_prepare_lock+0xc/0xec
> pc : [<c03eef38>]    lr : [<c03ec1f4>]    psr: 20000153
> sp : ee089de8  ip : 00000000  fp : 00000000
> r10: ee02f480  r9 : 00000001  r8 : 00000000
> r7 : ee031cc0  r6 : ee089e08  r5 : 00000000  r4 : ee02f480
> r3 : 00100100  r2 : 00200200  r1 : 0000091e  r0 : 00000001
> Flags: nzCv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment kernel
> Control: 10c5387d  Table: 4000404a  DAC: 00000015
> Process swapper/0 (pid: 1, stack limit = 0xee088238)
> Stack: (0xee089de8 to 0xee08a000)
> 9de0:                   ee7c8f14 c03f0ec8 ee089e08 00000000 c0718dc8 00000001
> 9e00: 00000000 c04ee0f0 ee7e0844 00000001 00000181 c04edb58 ee2bd320 00000000
> 9e20: 00000000 c011dc5c ee16a1e0 00000000 00000000 c0718dc8 ee16a1e0 ee2bd1e0
> 9e40: c0641740 ee16a1e0 00000000 ee2bd320 c0718dc8 ee1d3e10 ee1d3e10 00000000
> 9e60: c0769a88 00000000 c0718dc8 00000000 00000000 c02c3124 c02c310c ee1d3e10
> 9e80: c07b4eec 00000000 c0769a88 c02c1d0c ee1d3e10 c0769a88 ee1d3e44 00000000
> 9ea0: c07091dc c02c1eb8 00000000 c0769a88 c02c1e2c c02c0544 ee005478 ee1676c0
> 9ec0: c0769a88 ee3a4e80 c0760ce8 c02c150c c0669b90 c0769a88 c0746cd8 c0769a88
> 9ee0: c0746cd8 ee2bc4c0 c0778c00 c02c24e0 00000000 c0746cd8 c0746cd8 c07091f0
> 9f00: 00000000 c0008944 c04f405c 00000025 ee00b000 60000153 c074ab00 00000000
> 9f20: 00000000 c074ab90 60000153 00000000 ef7fca5d c050860c 000000b6 c0036b88
> 9f40: c065ecc4 c06bc728 00000006 00000006 c074ab30 ef7fca40 c0739bdc 00000006
> 9f60: c0718dbc c0778c00 000000b6 c0718dc8 c06ed598 c06edd64 00000006 00000006
> 9f80: c06ed598 c003b438 00000000 c04e64f4 00000000 00000000 00000000 00000000
> 9fa0: 00000000 c04e64fc 00000000 c000e838 00000000 00000000 00000000 00000000
> 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 c0c0c0c0 c0c0c0c0
> [<c03eef38>] (__clk_put) from [<c03f0ec8>] (of_clk_set_defaults+0xe0/0x2c0)
> [<c03f0ec8>] (of_clk_set_defaults) from [<c02c3124>] (platform_drv_probe+0x18/0xa4)
> [<c02c3124>] (platform_drv_probe) from [<c02c1d0c>] (driver_probe_device+0x10c/0x22c)
> [<c02c1d0c>] (driver_probe_device) from [<c02c1eb8>] (__driver_attach+0x8c/0x90)
> [<c02c1eb8>] (__driver_attach) from [<c02c0544>] (bus_for_each_dev+0x54/0x88)
> [<c02c0544>] (bus_for_each_dev) from [<c02c150c>] (bus_add_driver+0xd4/0x1d0)
> [<c02c150c>] (bus_add_driver) from [<c02c24e0>] (driver_register+0x78/0xf4)
> [<c02c24e0>] (driver_register) from [<c07091f0>] (fimc_md_init+0x14/0x30)
> [<c07091f0>] (fimc_md_init) from [<c0008944>] (do_one_initcall+0x80/0x1d0)
> [<c0008944>] (do_one_initcall) from [<c06edd64>] (kernel_init_freeable+0x108/0x1d4)
> [<c06edd64>] (kernel_init_freeable) from [<c04e64fc>] (kernel_init+0x8/0xec)
> [<c04e64fc>] (kernel_init) from [<c000e838>] (ret_from_fork+0x14/0x3c)
> Code: ebfff4ae e5943014 e5942018 e3530000 (e5823000)
> 
> Let's create a per-user handle here so that clk_put() can
> properly unlink it and free the handle. Now that we allocate a
> clk structure here we need to free it if __clk_get() fails so
> bury the __clk_get() call in __of_clk_get_from_provider(). We
> need to handle the same problem in clk_get_sys() so export
> __clk_free_clk() to clkdev.c and do the same thing, except let's
> do some more inline functions to make this code #ifdef free.
> 
> This fixes the above crash, properly calls __clk_get() when
> of_clk_get_from_provider() is called, and cleans up the clk
> structure on the error path of clk_get_sys().
> 
> Fixes: 035a61c314eb "clk: Make clk API return per-user struct clk instances"
> Reported-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> Reported-by: Alban Browaeys <alban.browaeys@gmail.com>
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
>  drivers/clk/clk.c    | 18 +++++++++++++----
>  drivers/clk/clk.h    | 19 +++++++++++++++++-
>  drivers/clk/clkdev.c | 56 ++++++++++++++++++++++------------------------------
>  3 files changed, 56 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 113456030d66..5469d7714f5d 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c

[snip]

> @@ -209,17 +205,13 @@ struct clk *clk_get_sys(const char *dev_id, const char *con_id)
>  	if (!cl)
>  		goto out;
>  
> -	if (!__clk_get(cl->clk)) {
> +	clk = __clk_create_clk(__clk_get_hw(cl->clk), dev_id, con_id);

We need to check for clk being an error either here or in __clk_get
because __clk_create_clk can return -ENOMEM.

> +	if (!__clk_get(clk)) {
> +		__clk_free_clk(clk);
>  		cl = NULL;
>  		goto out;
>  	}
>  
> -#if defined(CONFIG_COMMON_CLK)
> -	clk = __clk_create_clk(__clk_get_hw(cl->clk), dev_id, con_id);
> -#else
> -	clk = cl->clk;
> -#endif
> -
>  out:
>  	mutex_unlock(&clocks_mutex);

Otherwise it looks good to me.

Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>

Thanks,

Tomeu