Re: [PATCH 2/2] drm/msm/dpu: Remove dynamic allocation from atomic context
From: Jessica Zhang
Date: Fri Oct 22 2021 - 15:15:07 EST
On 10/22/2021 10:20 AM, Rob Clark wrote:
From: Rob Clark <robdclark@xxxxxxxxxxxx>
We know the upper bound on # of mixers (ie. two), so lets just allocate
this on the stack.
Fixes:
BUG: sleeping function called from invalid context at include/linux/sched/mm.h:201
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/0
INFO: lockdep is turned off.
irq event stamp: 43642
hardirqs last enabled at (43641): [<ffffffe24dd276bc>] cpuidle_enter_state+0x158/0x25c
hardirqs last disabled at (43642): [<ffffffe24dfff450>] enter_el1_irq_or_nmi+0x10/0x1c
softirqs last enabled at (43620): [<ffffffe24d4103fc>] __do_softirq+0x1e4/0x464
softirqs last disabled at (43615): [<ffffffe24d48bd90>] __irq_exit_rcu+0x104/0x150
CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 5.15.0-rc3-debug+ #105
Hardware name: Google Lazor (rev1 - 2) with LTE (DT)
Call trace:
dump_backtrace+0x0/0x18c
show_stack+0x24/0x30
dump_stack_lvl+0xa0/0xd4
dump_stack+0x18/0x34
___might_sleep+0x1e0/0x1f0
__might_sleep+0x78/0x8c
slab_pre_alloc_hook.constprop.0+0x48/0x6c
__kmalloc+0xc8/0x21c
dpu_crtc_vblank_callback+0x158/0x1f8
dpu_encoder_vblank_callback+0x70/0xc4
dpu_encoder_phys_vid_vblank_irq+0x50/0x12c
dpu_core_irq+0x1bc/0x1d0
dpu_irq+0x1c/0x28
msm_irq+0x34/0x40
__handle_irq_event_percpu+0x15c/0x308
handle_irq_event_percpu+0x3c/0x90
handle_irq_event+0x54/0x98
handle_level_irq+0xa0/0xd0
handle_irq_desc+0x2c/0x44
generic_handle_domain_irq+0x28/0x34
dpu_mdss_irq+0x90/0xe8
handle_irq_desc+0x2c/0x44
handle_domain_irq+0x54/0x80
gic_handle_irq+0xd4/0x148
call_on_irq_stack+0x2c/0x54
do_interrupt_handler+0x4c/0x64
el1_interrupt+0x30/0xd0
el1h_64_irq_handler+0x18/0x24
el1h_64_irq+0x78/0x7c
arch_local_irq_enable+0xc/0x14
cpuidle_enter+0x44/0x5c
do_idle+0x248/0x268
cpu_startup_entry+0x30/0x48
rest_init+0x188/0x19c
arch_call_rest_init+0x1c/0x28
start_kernel+0x704/0x744
__primary_switched+0xc0/0xc8
Fixes: 78d9b458cc21 ("drm/msm/dpu: Add CRC support for DPU")
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 0ae397044310..80c0ae688734 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -182,21 +182,19 @@ static int dpu_crtc_get_crc(struct drm_crtc *crtc)
{
struct dpu_crtc_state *crtc_state;
struct dpu_crtc_mixer *m;
- u32 *crcs;
+ u32 crcs[CRTC_DUAL_MIXERS];
int i = 0;
int rc = 0;
crtc_state = to_dpu_crtc_state(crtc->state);
- crcs = kcalloc(crtc_state->num_mixers, sizeof(*crcs), GFP_KERNEL);
- if (!crcs)
- return -ENOMEM;
+ static_assert(ARRAY_SIZE(crcs) == ARRAY_SIZE(crtc_state->mixers));
Getting a C90 compiler warning for static_assert():
In file included from ./include/linux/bits.h:22,
from ./include/linux/bitops.h:6,
from ./include/linux/kernel.h:12,
from ./include/linux/list.h:9,
from ./include/linux/wait.h:7,
from ./include/linux/wait_bit.h:8,
from ./include/linux/fs.h:6,
from ./include/linux/debugfs.h:15,
from drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c:10:
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c: In function
‘dpu_crtc_get_crc’:
./include/linux/build_bug.h:78:41: warning: ISO C90 forbids mixed
declarations and code [-Wdeclaration-after-statement]
78 | #define __static_assert(expr, msg, ...)
_Static_assert(expr, msg)
| ^~~~~~~~~~~~~~
./include/linux/build_bug.h:77:34: note: in expansion of macro
‘__static_assert’
77 | #define static_assert(expr, ...) __static_assert(expr,
##__VA_ARGS__, #expr)
| ^~~~~~~~~~~~~~~
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c:192:2: note: in expansion
of macro ‘static_assert’
192 | static_assert(ARRAY_SIZE(crcs) ==
ARRAY_SIZE(crtc_state->mixers));
| ^~~~~~~~~~~~~
Can be fixed by moving the static_assert() before `crtc_state = ...`
Thanks,
Jessica Zhang
/* Skip first 2 frames in case of "uncooked" CRCs */
if (crtc_state->crc_frame_skip_count < 2) {
crtc_state->crc_frame_skip_count++;
- goto cleanup;
+ return 0;
}
for (i = 0; i < crtc_state->num_mixers; ++i) {
@@ -210,16 +208,12 @@ static int dpu_crtc_get_crc(struct drm_crtc *crtc)
if (rc) {
DRM_DEBUG_DRIVER("MISR read failed\n");
- goto cleanup;
+ return rc;
}
}
- rc = drm_crtc_add_crc_entry(crtc, true,
+ return drm_crtc_add_crc_entry(crtc, true,
drm_crtc_accurate_vblank_count(crtc), crcs);
-
-cleanup:
- kfree(crcs);
- return rc;
}
static bool dpu_crtc_get_scanout_position(struct drm_crtc *crtc,