Hi On 24.06.2020 18:03, Takashi Iwai wrote: > The module argument passed to snd_card_new() must be a valid non-NULL > pointer when the module support is enabled. Since ASoC driver passes > the argument from each snd_soc_card definition, one may forget to set > the owner field and lead to a NULL module easily. > > For catching such an overlook, add a WARN_ON() in snd_card_new(). > Also, put the card->module assignment in the ifdef block for a very > minor optimization. > > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> I know that this is intended, but I would like to note that this patch reveals the following issue on Raspberry Pi 3B with ARM 32bit kernel compiled from multi_v7_defconfig: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 210 at sound/core/init.c:207 snd_card_new+0x378/0x398 [snd] Modules linked in: vc4(+) snd_soc_core ac97_bus snd_pcm_dmaengine bluetooth snd_pcm snd_timer crc32_arm_ce raspberrypi_hwmon snd soundcore ecdh_generic ecc bcm2835_thermal phy_generic CPU: 1 PID: 210 Comm: systemd-udevd Not tainted 5.8.0-rc1-00027-g81033c6b584b #1087 Hardware name: BCM2835 [<c03113c0>] (unwind_backtrace) from [<c030bcb4>] (show_stack+0x10/0x14) [<c030bcb4>] (show_stack) from [<c071cef8>] (dump_stack+0xd4/0xe8) [<c071cef8>] (dump_stack) from [<c0345bfc>] (__warn+0xdc/0xf4) [<c0345bfc>] (__warn) from [<c0345cc4>] (warn_slowpath_fmt+0xb0/0xb8) [<c0345cc4>] (warn_slowpath_fmt) from [<bf02ff74>] (snd_card_new+0x378/0x398 [snd]) [<bf02ff74>] (snd_card_new [snd]) from [<bf11f0b4>] (snd_soc_bind_card+0x280/0x99c [snd_soc_core]) [<bf11f0b4>] (snd_soc_bind_card [snd_soc_core]) from [<bf12f000>] (devm_snd_soc_register_card+0x34/0x6c [snd_soc_core]) [<bf12f000>] (devm_snd_soc_register_card [snd_soc_core]) from [<bf165654>] (vc4_hdmi_bind+0x43c/0x5f4 [vc4]) [<bf165654>] (vc4_hdmi_bind [vc4]) from [<c09d660c>] (component_bind_all+0xec/0x24c) [<c09d660c>] (component_bind_all) from [<bf15c44c>] (vc4_drm_bind+0xd4/0x174 [vc4]) [<bf15c44c>] (vc4_drm_bind [vc4]) from [<c09d6ac0>] (try_to_bring_up_master+0x160/0x1b0) [<c09d6ac0>] (try_to_bring_up_master) from [<c09d6f38>] (component_master_add_with_match+0xd0/0x104) [<c09d6f38>] (component_master_add_with_match) from [<bf15c588>] (vc4_platform_drm_probe+0x9c/0xbc [vc4]) [<bf15c588>] (vc4_platform_drm_probe [vc4]) from [<c09df740>] (platform_drv_probe+0x6c/0xa4) [<c09df740>] (platform_drv_probe) from [<c09dd6f0>] (really_probe+0x210/0x350) [<c09dd6f0>] (really_probe) from [<c09dd940>] (driver_probe_device+0x5c/0xb4) [<c09dd940>] (driver_probe_device) from [<c09ddb38>] (device_driver_attach+0x58/0x60) [<c09ddb38>] (device_driver_attach) from [<c09ddbc0>] (__driver_attach+0x80/0xbc) [<c09ddbc0>] (__driver_attach) from [<c09db820>] (bus_for_each_dev+0x68/0xb4) [<c09db820>] (bus_for_each_dev) from [<c09dc9f8>] (bus_add_driver+0x130/0x1e8) [<c09dc9f8>] (bus_add_driver) from [<c09de648>] (driver_register+0x78/0x110) [<c09de648>] (driver_register) from [<c0302038>] (do_one_initcall+0x50/0x220) [<c0302038>] (do_one_initcall) from [<c03db544>] (do_init_module+0x60/0x210) [<c03db544>] (do_init_module) from [<c03da4f8>] (load_module+0x1e34/0x2338) [<c03da4f8>] (load_module) from [<c03dac00>] (sys_finit_module+0xac/0xbc) [<c03dac00>] (sys_finit_module) from [<c03000c0>] (ret_fast_syscall+0x0/0x54) Exception stack(0xeded9fa8 to 0xeded9ff0) ... ---[ end trace 6414689569c2bc08 ]--- This warning is not present when booting ARM 64bit kernel, but I suspect that this is due to the differences in the kernel configuration. > --- > sound/core/init.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/sound/core/init.c b/sound/core/init.c > index b02a99766351..0478847ba2b8 100644 > --- a/sound/core/init.c > +++ b/sound/core/init.c > @@ -203,7 +203,10 @@ int snd_card_new(struct device *parent, int idx, const char *xid, > mutex_unlock(&snd_card_mutex); > card->dev = parent; > card->number = idx; > +#ifdef MODULE > + WARN_ON(!module); > card->module = module; > +#endif > INIT_LIST_HEAD(&card->devices); > init_rwsem(&card->controls_rwsem); > rwlock_init(&card->ctl_files_rwlock); Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
