On 6/22/2018 9:00 AM, Dave Airlie wrote:
> On 31 May 2018 at 20:02, Shirish S <shirish.s at amd.com> wrote:
>> mutex's lead to sleeps which should be avoided in
>> atomic context.
>> Hence this patch replaces it with the spin_locks.
>>
>> Below is the stack trace:
> I'm not sure I really like this series of patches, going around
> replacing ATOMIC and mutex with spinlocks
> isn't something that should be done lightly,
>
> In all the patches I haven't seen what spin lock or what causes us to
> be in an atomic state in the first
> place and why it is necessary that we are in an atomic state for such
> long sequences of code.
We have root caused the issue and reverted all the patches in this patch
series that tend to replace
mutex's with spinlock's.
Regards,
Shirish S
> Thanks,
> Dave.
>
>> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:**
>> in_atomic(): 1, irqs_disabled(): 1, pid: 89, name: kworker/u4:3
>> CPU: 1 PID: 89 Comm: kworker/u4:3 Tainted: G W 4.14.43 #8
>> Workqueue: events_unbound commit_work
>> Call Trace:
>> dump_stack+0x4d/0x63
>> ___might_sleep+0x11f/0x12e
>> mutex_lock+0x20/0x42
>> amdgpu_atom_execute_table+0x26/0x72
>> enable_disp_power_gating_v2_1+0x85/0xae
>> dce110_enable_display_power_gating+0x83/0x1b1
>> dce110_power_down_fe+0x4a/0x6d
>> dc_post_update_surfaces_to_stream+0x59/0x87
>> amdgpu_dm_do_flip+0x239/0x298
>> amdgpu_dm_commit_planes.isra.23+0x379/0x54b
>> ? drm_calc_timestamping_constants+0x14b/0x15c
>> amdgpu_dm_atomic_commit_tail+0x4fc/0x5d2
>> ? wait_for_common+0x5b/0x69
>> commit_tail+0x42/0x64
>> process_one_work+0x1b0/0x314
>> worker_thread+0x1cb/0x2c1
>> ? create_worker+0x1da/0x1da
>> kthread+0x156/0x15e
>> ? kthread_flush_work+0xea/0xea
>> ret_from_fork+0x22/0x40
>>
>> V2: Added stack trace in commit message.
>>
>> Signed-off-by: Shirish S <shirish.s at amd.com>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c | 2 +-
>> drivers/gpu/drm/amd/amdgpu/atom.c | 4 ++--
>> drivers/gpu/drm/amd/amdgpu/atom.h | 3 ++-
>> 3 files changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>> index bf872f6..ba3d4b9 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>> @@ -2033,7 +2033,7 @@ int amdgpu_atombios_init(struct amdgpu_device *adev)
>> return -ENOMEM;
>> }
>>
>> - mutex_init(&adev->mode_info.atom_context->mutex);
>> + spin_lock_init(&adev->mode_info.atom_context->lock);
>> if (adev->is_atom_fw) {
>> amdgpu_atomfirmware_scratch_regs_init(adev);
>> amdgpu_atomfirmware_allocate_fb_scratch(adev);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/atom.c b/drivers/gpu/drm/amd/amdgpu/atom.c
>> index 69500a8..bfd98f0 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/atom.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/atom.c
>> @@ -1261,7 +1261,7 @@ int amdgpu_atom_execute_table(struct atom_context *ctx, int index, uint32_t * pa
>> {
>> int r;
>>
>> - mutex_lock(&ctx->mutex);
>> + spin_lock(&ctx->lock);
>> /* reset data block */
>> ctx->data_block = 0;
>> /* reset reg block */
>> @@ -1274,7 +1274,7 @@ int amdgpu_atom_execute_table(struct atom_context *ctx, int index, uint32_t * pa
>> ctx->divmul[0] = 0;
>> ctx->divmul[1] = 0;
>> r = amdgpu_atom_execute_table_locked(ctx, index, params);
>> - mutex_unlock(&ctx->mutex);
>> + spin_unlock(&ctx->lock);
>> return r;
>> }
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/atom.h b/drivers/gpu/drm/amd/amdgpu/atom.h
>> index a391709..54063e2 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/atom.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/atom.h
>> @@ -26,6 +26,7 @@
>> #define ATOM_H
>>
>> #include <linux/types.h>
>> +#include <linux/spinlock_types.h>
>> #include <drm/drmP.h>
>>
>> #define ATOM_BIOS_MAGIC 0xAA55
>> @@ -125,7 +126,7 @@ struct card_info {
>>
>> struct atom_context {
>> struct card_info *card;
>> - struct mutex mutex;
>> + spinlock_t lock;
>> void *bios;
>> uint32_t cmd_table, data_table;
>> uint16_t *iio;
>> --
>> 2.7.4
>>
>> _______________________________________________
>> amd-gfx mailing list
>> amd-gfx at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
--
Regards,
Shirish S
