[PATCH] ASoC: da7219: Fix general protection fault in da7219_register_dai_clks

[Yong Zhi]

clkdev_drop(cl) does not null the removed cl, if da7219_register_dai_clks()
entered again after card removal, devm_clk_register() will return -EEXIST,
the goto err to clkdev_drop() will trigger board reboot.

Test commands:
   modprobe -r snd_sof_pci
   modprobe snd_sof_pci

The oops looks like:

da7219 i2c-DLGS7219:00: Using default DAI clk names: da7219-dai-wclk, da7219-dai-bclk
da7219 i2c-DLGS7219:00: Failed to register da7219-dai-wclk: -17
general protection fault: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:clkdev_drop+0x20/0x52
Call Trace:
 da7219_probe+0x52e/0x6dc [snd_soc_da7219]
 soc_probe_component+0x206/0x3a1
 snd_soc_bind_card+0x4ee/0x9a6
 devm_snd_soc_register_card+0x48/0x7b
 audio_probe+0x1f0/0x221 [snd_soc_sof_da7219_max98373]
 platform_drv_probe+0x89/0xa2
 really_probe+0x129/0x30d
 driver_probe_device+0x59/0xec
 ? driver_sysfs_remove+0x55/0x55
 bus_for_each_drv+0xa1/0xdc
 __device_attach+0xc2/0x146
 bus_probe_device+0x32/0x97
 device_add+0x311/0x3b4
 platform_device_add+0x184/0x1eb

Fix by marking (nullifying) the da7219->dai_clks_lookup[i]
after clkdev_drop().

Signed-off-by: Yong Zhi <yong.zhi at intel.com>
---
 sound/soc/codecs/da7219.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
index 153ea30b5a8f..54da7cfbb5f4 100644
--- a/sound/soc/codecs/da7219.c
+++ b/sound/soc/codecs/da7219.c
@@ -2369,8 +2369,10 @@ static void da7219_remove(struct snd_soc_component *component)
 
 #ifdef CONFIG_COMMON_CLK
 	for (i = DA7219_DAI_NUM_CLKS - 1; i >= 0; --i) {
-		if (da7219->dai_clks_lookup[i])
+		if (da7219->dai_clks_lookup[i]) {
 			clkdev_drop(da7219->dai_clks_lookup[i]);
+			da7219->dai_clks_lookup[i] = NULL;
+		}
 	}
 #endif
 
-- 
2.7.4