[PATCH v4, 1/2] drm: Check output polling initialized before disabling

Shradha Gupta
2024-02-02T06:43:30Z

In drm_kms_helper_poll_disable() check if output polling
support is initialized before disabling polling. If not flag
this as a warning.
Additionally in drm_mode_config_helper_suspend() and
drm_mode_config_helper_resume() calls, that re the callers of these
functions, avoid invoking them if polling is not initialized.
For drivers like hyperv-drm, that do not initialize connector
polling, if suspend is called without this check, it leads to
suspend failure with following stack
[ 770.719392] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[ 770.720592] printk: Suspending console(s) (use no_console_suspend to debug)
[ 770.948823] ------------[ cut here ]------------
[ 770.948824] WARNING: CPU: 1 PID: 17197 at kernel/workqueue.c:3162 __flush_work.isra.0+0x212/0x230
[ 770.948831] Modules linked in: rfkill nft_counter xt_conntrack xt_owner udf nft_compat crc_itu_t nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables nfnetlink vfat fat mlx5_ib ib_uverbs ib_core mlx5_core intel_rapl_msr intel_rapl_common kvm_amd ccp mlxfw kvm psample hyperv_drm tls drm_shmem_helper drm_kms_helper irqbypass pcspkr syscopyarea sysfillrect sysimgblt hv_balloon hv_utils joydev drm fuse xfs libcrc32c pci_hyperv pci_hyperv_intf sr_mod sd_mod cdrom t10_pi sg hv_storvsc scsi_transport_fc hv_netvsc serio_raw hyperv_keyboard hid_hyperv crct10dif_pclmul crc32_pclmul crc32c_intel hv_vmbus ghash_clmulni_intel dm_mirror dm_region_hash dm_log dm_mod
[ 770.948863] CPU: 1 PID: 17197 Comm: systemd-sleep Not tainted 5.14.0-362.2.1.el9_3.x86_64 #1
[ 770.948865] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 05/09/2022
[ 770.948866] RIP: 0010:__flush_work.isra.0+0x212/0x230
[ 770.948869] Code: 8b 4d 00 4c 8b 45 08 89 ca 48 c1 e9 04 83 e2 08 83 e1 0f 83 ca 02 89 c8 48 0f ba 6d 00 03 e9 25 ff ff ff 0f 0b e9 4e ff ff ff <0f> 0b 45 31 ed e9 44 ff ff ff e8 8f 89 b2 00 66 66 2e 0f 1f 84 00
[ 770.948870] RSP: 0018:ffffaf4ac213fb10 EFLAGS: 00010246
[ 770.948871] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8c992857
[ 770.948872] RDX: 0000000000000001 RSI: 0000000000000001 RDI: ffff9aad82b00330
[ 770.948873] RBP: ffff9aad82b00330 R08: 0000000000000000 R09: ffff9aad87ee3d10
[ 770.948874] R10: 0000000000000200 R11: 0000000000000000 R12: ffff9aad82b00330
[ 770.948874] R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
[ 770.948875] FS: 00007ff1b2f6bb40(0000) GS:ffff9aaf37d00000(0000) knlGS:0000000000000000
[ 770.948878] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 770.948878] CR2: 0000555f345cb666 CR3: 00000001462dc005 CR4: 0000000000370ee0
[ 770.948879] Call Trace:
[ 770.948880] <TASK>
[ 770.948881] ? show_trace_log_lvl+0x1c4/0x2df
[ 770.948884] ? show_trace_log_lvl+0x1c4/0x2df
[ 770.948886] ? __cancel_work_timer+0x103/0x190
[ 770.948887] ? __flush_work.isra.0+0x212/0x230
[ 770.948889] ? __warn+0x81/0x110
[ 770.948891] ? __flush_work.isra.0+0x212/0x230
[ 770.948892] ? report_bug+0x10a/0x140
[ 770.948895] ? handle_bug+0x3c/0x70
[ 770.948898] ? exc_invalid_op+0x14/0x70
[ 770.948899] ? asm_exc_invalid_op+0x16/0x20
[ 770.948903] ? __flush_work.isra.0+0x212/0x230
[ 770.948905] __cancel_work_timer+0x103/0x190
[ 770.948907] ? _raw_spin_unlock_irqrestore+0xa/0x30
[ 770.948910] drm_kms_helper_poll_disable+0x1e/0x40 [drm_kms_helper]
[ 770.948923] drm_mode_config_helper_suspend+0x1c/0x80 [drm_kms_helper]
[ 770.948933] ? __pfx_vmbus_suspend+0x10/0x10 [hv_vmbus]
[ 770.948942] hyperv_vmbus_suspend+0x17/0x40 [hyperv_drm]
[ 770.948944] ? __pfx_vmbus_suspend+0x10/0x10 [hv_vmbus]
[ 770.948951] dpm_run_callback+0x4c/0x140
[ 770.948954] __device_suspend_noirq+0x74/0x220
[ 770.948956] dpm_noirq_suspend_devices+0x148/0x2a0
[ 770.948958] dpm_suspend_end+0x54/0xe0
[ 770.948960] create_image+0x14/0x290
[ 770.948963] hibernation_snapshot+0xd6/0x200
[ 770.948964] hibernate.cold+0x8b/0x1fb
[ 770.948967] state_store+0xcd/0xd0
[ 770.948969] kernfs_fop_write_iter+0x124/0x1b0
[ 770.948973] new_sync_write+0xff/0x190
[ 770.948976] vfs_write+0x1ef/0x280
[ 770.948978] ksys_write+0x5f/0xe0
[ 770.948979] do_syscall_64+0x5c/0x90
[ 770.948981] ? syscall_exit_work+0x103/0x130
[ 770.948983] ? syscall_exit_to_user_mode+0x12/0x30
[ 770.948985] ? do_syscall_64+0x69/0x90
[ 770.948986] ? do_syscall_64+0x69/0x90
[ 770.948987] ? do_user_addr_fault+0x1d6/0x6a0
[ 770.948989] ? do_syscall_64+0x69/0x90
[ 770.948990] ? exc_page_fault+0x62/0x150
[ 770.948992] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[ 770.948995] RIP: 0033:0x7ff1b293eba7
[ 770.949010] Code: 0b 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
[ 770.949011] RSP: 002b:00007ffde3912128 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 770.949012] RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007ff1b293eba7
[ 770.949013] RDX: 0000000000000005 RSI: 00007ffde3912210 RDI: 0000000000000004
[ 770.949014] RBP: 00007ffde3912210 R08: 000055d7dd4c9510 R09: 00007ff1b29b14e0
[ 770.949014] R10: 00007ff1b29b13e0 R11: 0000000000000246 R12: 0000000000000005
[ 770.949015] R13: 000055d7dd4c53e0 R14: 0000000000000005 R15: 00007ff1b29f69e0
[ 770.949016] </TASK>
[ 770.949017] ---[ end trace e6fa0618bfa2f31d ]---

Built-on: Rhel9, Ubuntu22
Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
---
Changes in v4
* clubbed similar patches together and added a cover letter
Changes in v3
* Also added checks in the _suspend and _resume calls to avoid driver bugs
* Added WARN_ON around the checks in _enable and _disable calls
* Fixed the patch description to reflect new changes
Changes in v2
* Moved the poll_enabled check in drm_kms_helper_poll_disable()
* Reworded the patch description based on new changes
---
drivers/gpu/drm/drm_modeset_helper.c | 19 ++++++++++++++++---
drivers/gpu/drm/drm_probe_helper.c | 13 +++++++++++--
2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_modeset_helper.c b/drivers/gpu/drm/drm_modeset_helper.c
index f858dfedf2cf..2c582020cb42 100644
--- a/drivers/gpu/drm/drm_modeset_helper.c
+++ b/drivers/gpu/drm/drm_modeset_helper.c
@@ -193,13 +193,22 @@ int drm_mode_config_helper_suspend(struct drm_device *dev)

if (!dev)
return 0;
+ /*
+ * Don't disable polling if it was never initialized
+ */
+ if (dev->mode_config.poll_enabled)
+ drm_kms_helper_poll_disable(dev);

- drm_kms_helper_poll_disable(dev);
drm_fb_helper_set_suspend_unlocked(dev->fb_helper, 1);
state = drm_atomic_helper_suspend(dev);
if (IS_ERR(state)) {
drm_fb_helper_set_suspend_unlocked(dev->fb_helper, 0);
- drm_kms_helper_poll_enable(dev);
+ /*
+ * Don't enable polling if it was never initialized
+ */
+ if (dev->mode_config.poll_enabled)
+ drm_kms_helper_poll_enable(dev);
+
return PTR_ERR(state);
}

@@ -239,7 +248,11 @@ int drm_mode_config_helper_resume(struct drm_device *dev)
dev->mode_config.suspend_state = NULL;

drm_fb_helper_set_suspend_unlocked(dev->fb_helper, 0);
- drm_kms_helper_poll_enable(dev);
+ /*
+ * Don't enable polling if it is not initialized
+ */
+ if (dev->mode_config.poll_enabled)
+ drm_kms_helper_poll_enable(dev);

return ret;
}
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 3f479483d7d8..bd76603dc387 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -293,14 +293,17 @@ static void reschedule_output_poll_work(struct drm_device *dev)
* Drivers can call this helper from their device resume implementation. It is
* not an error to call this even when output polling isn't enabled.
*
+ * If device polling was never initialized before, this call will trigger a
+ * warning and return.
+ *
* Note that calls to enable and disable polling must be strictly ordered, which
* is automatically the case when they're only call from suspend/resume
* callbacks.
*/
void drm_kms_helper_poll_enable(struct drm_device *dev)
{
- if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll ||
- dev->mode_config.poll_running)
+ if (drm_WARN_ON_ONCE(dev, !dev->mode_config.poll_enabled) ||
+ !drm_kms_helper_poll || dev->mode_config.poll_running)
return;

if (drm_kms_helper_enable_hpd(dev) ||
@@ -871,12 +874,18 @@ EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
* not an error to call this even when output polling isn't enabled or already
* disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable().
*
+ * If however, the polling was never initialized, this call will trigger a
+ * warning and return
+ *
* Note that calls to enable and disable polling must be strictly ordered, which
* is automatically the case when they're only call from suspend/resume
* callbacks.
*/
void drm_kms_helper_poll_disable(struct drm_device *dev)
{
+ if (drm_WARN_ON(dev, !dev->mode_config.poll_enabled))
+ return;
+
if (dev->mode_config.poll_running)
drm_kms_helper_disable_hpd(dev);

--
2.34.1