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riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

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When CONFIG_DEBUG_RT_MUTEXES=y, mutex_lock->rt_mutex_try_acquire
would change from rt_mutex_cmpxchg_acquire to
rt_mutex_slowtrylock():
	raw_spin_lock_irqsave(&lock->wait_lock, flags);
	ret = __rt_mutex_slowtrylock(lock);
	raw_spin_unlock_irqrestore(&lock->wait_lock, flags);

Because queued_spin_#ops to ticket_#ops is changed one by one by
jump_label, raw_spin_lock/unlock would cause a deadlock during the
changing.

That means in arch/riscv/kernel/jump_label.c:
1.
arch_jump_label_transform_queue() ->
mutex_lock(&text_mutex); +-> raw_spin_lock  -> queued_spin_lock
			 |-> raw_spin_unlock -> queued_spin_unlock
patch_insn_write -> change the raw_spin_lock to ticket_lock
mutex_unlock(&text_mutex);
...

2. /* Dirty the lock value */
arch_jump_label_transform_queue() ->
mutex_lock(&text_mutex); +-> raw_spin_lock -> *ticket_lock*
                         |-> raw_spin_unlock -> *queued_spin_unlock*
			  /* BUG: ticket_lock with queued_spin_unlock */
patch_insn_write  ->  change the raw_spin_unlock to ticket_unlock
mutex_unlock(&text_mutex);
...

3. /* Dead lock */
arch_jump_label_transform_queue() ->
mutex_lock(&text_mutex); +-> raw_spin_lock -> ticket_lock /* deadlock! */
                         |-> raw_spin_unlock -> ticket_unlock
patch_insn_write -> change other raw_spin_#op -> ticket_#op
mutex_unlock(&text_mutex);

So, the solution is to disable mutex usage of
arch_jump_label_transform_queue() during early_boot_irqs_disabled, just
like we have done for stop_machine.

Reported-by: Conor Dooley <conor@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Fixes: ab83647fad ("riscv: Add qspinlock support")
Link: https://lore.kernel.org/linux-riscv/CAJF2gTQwYTGinBmCSgVUoPv0_q4EPt_+WiyfUA1HViAKgUzxAg@mail.gmail.com/T/#mf488e6347817fca03bb93a7d34df33d8615b3775
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Nam Cao <namcao@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241130153310.3349484-1-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Guo Ren 2024-11-30 10:33:10 -05:00 committed by Palmer Dabbelt
parent fac04efc5c
commit b3134b8c1a
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GPG Key ID: EF4CA1502CCBAB41
1 changed files with 9 additions and 3 deletions
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12
arch/riscv/kernel/jump_label.c
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@ -36,9 +36,15 @@ bool arch_jump_label_transform_queue(struct jump_entry *entry,
insn = RISCV_INSN_NOP;
}
mutex_lock(&text_mutex);
patch_insn_write(addr, &insn, sizeof(insn));
mutex_unlock(&text_mutex);
if (early_boot_irqs_disabled) {
riscv_patch_in_stop_machine = 1;
patch_insn_write(addr, &insn, sizeof(insn));
riscv_patch_in_stop_machine = 0;
} else {
mutex_lock(&text_mutex);
patch_insn_write(addr, &insn, sizeof(insn));
mutex_unlock(&text_mutex);
}
return true;
}