clkdev: Always allocate a struct clk and call __clk_get() w/ CCF

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
use a union 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>
Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Alban Browaeys <prahal@yahoo.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

1 files changed, 27 insertions, 32 deletions

diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 29a1ab7af4b8..043fd3633373 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -29,6 +29,20 @@ static DEFINE_MUTEX(clocks_mutex);
 
 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 
+static struct clk *__of_clk_get_by_clkspec(struct of_phandle_args *clkspec,
+                                         const char *dev_id, const char *con_id)
+{
+        struct clk *clk;
+
+        if (!clkspec)
+                return ERR_PTR(-EINVAL);
+
+        of_clk_lock();
+        clk = __of_clk_get_from_provider(clkspec, dev_id, con_id);
+        of_clk_unlock();
+        return clk;
+}
+
 /**
  * of_clk_get_by_clkspec() - Lookup a clock form a clock provider
  * @clkspec: pointer to a clock specifier data structure
@@ -39,22 +53,11 @@ static DEFINE_MUTEX(clocks_mutex);
  */
 struct clk *of_clk_get_by_clkspec(struct of_phandle_args *clkspec)
 {
-        struct clk *clk;
-
-        if (!clkspec)
-                return ERR_PTR(-EINVAL);
-
-        of_clk_lock();
-        clk = __of_clk_get_from_provider(clkspec);
-
-        if (!IS_ERR(clk) && !__clk_get(clk))
-                clk = ERR_PTR(-ENOENT);
-
-        of_clk_unlock();
-        return clk;
+        return __of_clk_get_by_clkspec(clkspec, NULL, __func__);
 }
 
-static struct clk *__of_clk_get(struct device_node *np, int index)
+static struct clk *__of_clk_get(struct device_node *np, int index,
+                               const char *dev_id, const char *con_id)
 {
         struct of_phandle_args clkspec;
         struct clk *clk;
@@ -68,7 +71,7 @@ static struct clk *__of_clk_get(struct device_node *np, int index)
         if (rc)
                 return ERR_PTR(rc);
 
-        clk = of_clk_get_by_clkspec(&clkspec);
+        clk = __of_clk_get_by_clkspec(&clkspec, dev_id, con_id);
         of_node_put(clkspec.np);
 
         return clk;
@@ -76,12 +79,7 @@ static struct clk *__of_clk_get(struct device_node *np, int index)
 
 struct clk *of_clk_get(struct device_node *np, int index)
 {
-        struct clk *clk = __of_clk_get(np, index);
-
-        if (!IS_ERR(clk))
-                clk = __clk_create_clk(__clk_get_hw(clk), np->full_name, NULL);
-
-        return clk;
+        return __of_clk_get(np, index, np->full_name, NULL);
 }
 EXPORT_SYMBOL(of_clk_get);
 
@@ -102,12 +100,10 @@ static struct clk *__of_clk_get_by_name(struct device_node *np,
                  */
                 if (name)
                         index = of_property_match_string(np, "clock-names", name);
-                clk = __of_clk_get(np, index);
+                clk = __of_clk_get(np, index, dev_id, name);
                 if (!IS_ERR(clk)) {
-                        clk = __clk_create_clk(__clk_get_hw(clk), dev_id, name);
                         break;
-                }
-                else if (name && index >= 0) {
+                } else if (name && index >= 0) {
                         if (PTR_ERR(clk) != -EPROBE_DEFER)
                                 pr_err("ERROR: could not get clock %s:%s(%i)\n",
                                         np->full_name, name ? name : "", index);
@@ -209,17 +205,16 @@ 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);
+        if (IS_ERR(clk))
+                goto out;
+
+        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);