It turns out that if you happen to have a kernel config where
CONFIG_DRM_PANIC is disabled and spinlock debugging is enabled, along with
KMS being enabled - we'll end up trying to acquire an uninitialized
spin_lock with drm_panic_lock() when we try to do a commit:
rvkms rvkms.0: [drm:drm_atomic_commit] committing 0000000068d2ade1
INFO: trying to register non-static key.
The code is fine but needs lockdep annotation, or maybe
you didn't initialize this object before use?
turning off the locking correctness validator.
CPU: 4 PID: 1347 Comm: modprobe Not tainted 6.10.0-rc1Lyude-Test+ #272
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20240524-3.fc40 05/24/2024
Call Trace:
<TASK>
dump_stack_lvl+0x77/0xa0
assign_lock_key+0x114/0x120
register_lock_class+0xa8/0x2c0
__lock_acquire+0x7d/0x2bd0
? __vmap_pages_range_noflush+0x3a8/0x550
? drm_atomic_helper_swap_state+0x2ad/0x3a0
lock_acquire+0xec/0x290
? drm_atomic_helper_swap_state+0x2ad/0x3a0
? lock_release+0xee/0x310
_raw_spin_lock_irqsave+0x4e/0x70
? drm_atomic_helper_swap_state+0x2ad/0x3a0
drm_atomic_helper_swap_state+0x2ad/0x3a0
drm_atomic_helper_commit+0xb1/0x270
drm_atomic_commit+0xaf/0xe0
? __pfx___drm_printfn_info+0x10/0x10
drm_client_modeset_commit_atomic+0x1a1/0x250
drm_client_modeset_commit_locked+0x4b/0x180
drm_client_modeset_commit+0x27/0x50
__drm_fb_helper_restore_fbdev_mode_unlocked+0x76/0x90
drm_fb_helper_set_par+0x38/0x40
fbcon_init+0x3c4/0x690
visual_init+0xc0/0x120
do_bind_con_driver+0x409/0x4c0
do_take_over_console+0x233/0x280
do_fb_registered+0x11f/0x210
fbcon_fb_registered+0x2c/0x60
register_framebuffer+0x248/0x2a0
__drm_fb_helper_initial_config_and_unlock+0x58a/0x720
drm_fbdev_generic_client_hotplug+0x6e/0xb0
drm_client_register+0x76/0xc0
_RNvXs_CsHeezP08sTT_5rvkmsNtB4_5RvkmsNtNtCs1cdwasc6FUb_6kernel8platform6Driver5probe+0xed2/0x1060 [rvkms]
? _RNvMs_NtCs1cdwasc6FUb_6kernel8platformINtB4_7AdapterNtCsHeezP08sTT_5rvkms5RvkmsE14probe_callbackBQ_+0x2b/0x70 [rvkms]
? acpi_dev_pm_attach+0x25/0x110
? platform_probe+0x6a/0xa0
? really_probe+0x10b/0x400
? __driver_probe_device+0x7c/0x140
? driver_probe_device+0x22/0x1b0
? __device_attach_driver+0x13a/0x1c0
? __pfx___device_attach_driver+0x10/0x10
? bus_for_each_drv+0x114/0x170
? __device_attach+0xd6/0x1b0
? bus_probe_device+0x9e/0x120
? device_add+0x288/0x4b0
? platform_device_add+0x75/0x230
? platform_device_register_full+0x141/0x180
? rust_helper_platform_device_register_simple+0x85/0xb0
? _RNvMs2_NtCs1cdwasc6FUb_6kernel8platformNtB5_6Device13create_simple+0x1d/0x60
? _RNvXs0_CsHeezP08sTT_5rvkmsNtB5_5RvkmsNtCs1cdwasc6FUb_6kernel6Module4init+0x11e/0x160 [rvkms]
? 0xffffffffc083f000
? init_module+0x20/0x1000 [rvkms]
? kernfs_xattr_get+0x3e/0x80
? do_one_initcall+0x148/0x3f0
? __lock_acquire+0x5ef/0x2bd0
? __lock_acquire+0x5ef/0x2bd0
? __lock_acquire+0x5ef/0x2bd0
? put_cpu_partial+0x51/0x1d0
? lock_acquire+0xec/0x290
? put_cpu_partial+0x51/0x1d0
? lock_release+0xee/0x310
? put_cpu_partial+0x51/0x1d0
? fs_reclaim_acquire+0x69/0xf0
? lock_acquire+0xec/0x290
? fs_reclaim_acquire+0x69/0xf0
? kfree+0x22f/0x340
? lock_release+0xee/0x310
? kmalloc_trace_noprof+0x48/0x340
? do_init_module+0x22/0x240
? kmalloc_trace_noprof+0x155/0x340
? do_init_module+0x60/0x240
? __se_sys_finit_module+0x2e0/0x3f0
? do_syscall_64+0xa4/0x180
? syscall_exit_to_user_mode+0x108/0x140
? do_syscall_64+0xb0/0x180
? vma_end_read+0xd0/0xe0
? do_user_addr_fault+0x309/0x640
? clear_bhb_loop+0x45/0xa0
? clear_bhb_loop+0x45/0xa0
? clear_bhb_loop+0x45/0xa0
? entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
Fix this by stubbing these macros out when this config option isn't
enabled, along with fixing the unused variable warning that introduces.
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
drivers/gpu/drm/drm_atomic_helper.c | 2 +-
include/drm/drm_panic.h | 8 ++++++--
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index fb97b51b38f15..dd5caa8030aa3 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -3017,7 +3017,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state,
bool stall)
{
int i, ret;
- unsigned long flags;
+ unsigned long __maybe_unused flags;
struct drm_connector *connector;
struct drm_connector_state *old_conn_state, *new_conn_state;
struct drm_crtc *crtc;
diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h
index 822dbb1aa9d6f..9cd4239f09286 100644
--- a/include/drm/drm_panic.h
+++ b/include/drm/drm_panic.h
@@ -52,6 +52,8 @@ struct drm_scanout_buffer {
unsigned int pitch[DRM_FORMAT_MAX_PLANES];
};
+#ifdef CONFIG_DRM_PANIC
+
/**
* drm_panic_trylock - try to enter the panic printing critical section
* @dev: struct drm_device
@@ -137,13 +139,15 @@ struct drm_scanout_buffer {
#define drm_panic_unlock(dev, flags) \
raw_spin_unlock_irqrestore(&(dev)->mode_config.panic_lock, flags)
-#ifdef CONFIG_DRM_PANIC
-
void drm_panic_register(struct drm_device *dev);
void drm_panic_unregister(struct drm_device *dev);
#else
+#define drm_panic_trylock(dev, flags) (true)
+#define drm_panic_lock(dev, flags)
+#define drm_panic_unlock(dev, flags)
+
static inline void drm_panic_register(struct drm_device *dev) {}
static inline void drm_panic_unregister(struct drm_device *dev) {}
--
2.45.2
