On Fri, Oct 22, 2021 at 12:15 PM Jessica Zhang jesszhan@codeaurora.org wrote:

On 10/22/2021 10:20 AM, Rob Clark wrote:

...

From: Rob Clark robdclark@chromium.org

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@chromium.org

---

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 = ...`

I was trying to avoid moving that because I've seen tools flag things like that as use-before-init before. But I guess I can use BUILD_BUG_ON() instead.

BR, -R

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,