wifi: ath12k: fix context switch in panic notifier issue#915
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MilanoPipo wants to merge 1 commit intoqualcomm-linux:tech/net/athfrom
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wifi: ath12k: fix context switch in panic notifier issue#915MilanoPipo wants to merge 1 commit intoqualcomm-linux:tech/net/athfrom
MilanoPipo wants to merge 1 commit intoqualcomm-linux:tech/net/athfrom
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Call Stack: Voluntary context switch within RCU read-side critical section! WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x4c4/0x508, CPU#1: bash/817 CPU: 1 UID: 0 PID: 817 Comm: bash Tainted: G W 7.0.0-rc3 qualcomm-linux#1 PREEMPT Tainted: [W]=WARN Hardware name: Qualcomm Technologies, Inc. Hamoa IoT EVK (DT) pstate: 614000c5 (nZCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : rcu_note_context_switch+0x4c4/0x508 lr : rcu_note_context_switch+0x4c4/0x508 sp : ffff800085eeb7f0 x29: ffff800085eeb7f0 x28: ffff0008044fd640 x27: 0000000000000000 x26: 0000000000000000 x25: ffffd83dbc89c100 x24: ffff00081e668000 x23: 0000000000000000 x22: ffff0008044fd640 x21: ffffd83dbd9a6760 x20: 0000000000000000 x19: ffff008f386a2040 x18: 0000000000003fb8 x17: 2020202020202020 x16: ffffd83dbb6147b0 x15: 00000000000006a7 x14: 0000000000000001 x13: 00000000000006a6 x12: 00000000fffff6a5 x11: ffffd83dbd3b2a90 x10: ffffd83dbd414a88 x9 : ffffd83dbd3b2b10 x8 : ffffd83dbd40ab10 x7 : 0000000000003f70 x6 : 00000000000006a5 x5 : ffff008f3868d448 x4 : 80000000fffff6a5 x3 : ffff28517be05000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0008044fd640 Call trace: rcu_note_context_switch+0x4c4/0x508 (P) __schedule+0xbc/0x1204 schedule+0x34/0x110 schedule_timeout+0x84/0x11c __mhi_device_get_sync+0x164/0x228 [mhi] mhi_device_get_sync+0x1c/0x3c [mhi] ath12k_wifi7_pci_bus_wake_up+0x20/0x2c [ath12k_wifi7] ath12k_pci_read32+0x58/0x350 [ath12k] ath12k_pci_clear_dbg_registers+0x28/0xb8 [ath12k] ath12k_pci_panic_handler+0x20/0x44 [ath12k] ath12k_core_panic_handler+0x28/0x3c [ath12k] notifier_call_chain+0x78/0x1c0 atomic_notifier_call_chain+0x3c/0x5c In ath12k_pci_panic_handler() many reset related registers need to be read/written. Since Q6 can be in a power‑saving mode (M1/M2), the common PCI read/write APIs in ath12k explicitly wake up Q6 and wait until it reaches the M0 state before issuing the read/write. The wait may result in a context switch. Panic handler is in a atomic RCU read process, we need to avoid context switch in this process. Add a flag to avoid waking up Q6 in panic handler process. Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.115823.3 Signed-off-by: Yingying Tang <yingying.tang@oss.qualcomm.com>
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Call Stack:
Voluntary context switch within RCU read-side critical section! WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x4c4/0x508, CPU#1: bash/817
CPU: 1 UID: 0 PID: 817 Comm: bash Tainted: G W 7.0.0-rc3 #1 PREEMPT
Tainted: [W]=WARN
Hardware name: Qualcomm Technologies, Inc. Hamoa IoT EVK (DT)
pstate: 614000c5 (nZCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : rcu_note_context_switch+0x4c4/0x508
lr : rcu_note_context_switch+0x4c4/0x508
sp : ffff800085eeb7f0
x29: ffff800085eeb7f0 x28: ffff0008044fd640 x27: 0000000000000000
x26: 0000000000000000 x25: ffffd83dbc89c100 x24: ffff00081e668000
x23: 0000000000000000 x22: ffff0008044fd640 x21: ffffd83dbd9a6760
x20: 0000000000000000 x19: ffff008f386a2040 x18: 0000000000003fb8
x17: 2020202020202020 x16: ffffd83dbb6147b0 x15: 00000000000006a7
x14: 0000000000000001 x13: 00000000000006a6 x12: 00000000fffff6a5
x11: ffffd83dbd3b2a90 x10: ffffd83dbd414a88 x9 : ffffd83dbd3b2b10
x8 : ffffd83dbd40ab10 x7 : 0000000000003f70 x6 : 00000000000006a5
x5 : ffff008f3868d448 x4 : 80000000fffff6a5 x3 : ffff28517be05000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0008044fd640
Call trace:
rcu_note_context_switch+0x4c4/0x508 (P)
__schedule+0xbc/0x1204
schedule+0x34/0x110
schedule_timeout+0x84/0x11c
__mhi_device_get_sync+0x164/0x228 [mhi]
mhi_device_get_sync+0x1c/0x3c [mhi]
ath12k_wifi7_pci_bus_wake_up+0x20/0x2c [ath12k_wifi7]
ath12k_pci_read32+0x58/0x350 [ath12k]
ath12k_pci_clear_dbg_registers+0x28/0xb8 [ath12k]
ath12k_pci_panic_handler+0x20/0x44 [ath12k]
ath12k_core_panic_handler+0x28/0x3c [ath12k]
notifier_call_chain+0x78/0x1c0
atomic_notifier_call_chain+0x3c/0x5c
In ath12k_pci_panic_handler() many reset related registers need to be read/written.
Since Q6 can be in a power‑saving mode (M1/M2), the common PCI read/write APIs in ath12k explicitly wake up Q6 and wait until it reaches the M0 state before issuing the read/write. The wait may result in a context switch.
Panic handler is in a atomic RCU read process, we need to avoid context switch in this process.
Add a flag to avoid waking up Q6 in panic handler process.
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.115823.3