[RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[guoren]

From: Guo Ren <guoren@linux.alibaba.com>

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: ab83647fadae ("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>
---
 arch/riscv/kernel/jump_label.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
index 6eee6f736f68..654ed159c830 100644
--- a/arch/riscv/kernel/jump_label.c
+++ b/arch/riscv/kernel/jump_label.c
@@ -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;
 }
-- 
2.40.1


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Re: [RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[Conor Dooley]

[-- Attachment #1.1: Type: text/plain, Size: 1847 bytes --]

On Sat, Nov 30, 2024 at 10:33:10AM -0500, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
> 
> 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>

Tested-by: Conor Dooley <conor.dooley@microchip.com>

Thanks,
Conor.

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[-- Attachment #2: Type: text/plain, Size: 161 bytes --]

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Re: [RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[Alexandre Ghiti]

Hi Guo,

On 30/11/2024 16:33, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> 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: ab83647fadae ("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>
> ---
>   arch/riscv/kernel/jump_label.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> index 6eee6f736f68..654ed159c830 100644
> --- a/arch/riscv/kernel/jump_label.c
> +++ b/arch/riscv/kernel/jump_label.c
> @@ -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;
>   }


Sorry for the late answer, I've been sick lately!

Thank you very much for looking into this and finding this not-so-bad 
solution! I remind everyone that this is a temporary solution until we 
can use an alternative instead of a static key.

You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>

The revert is still on the table IMO, let's Palmer decide.

Thank you again Guo, really appreciate you took the time to find this 
solution!

Alex


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Re: [RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[Guo Ren]

On Wed, Dec 4, 2024 at 4:27 PM Alexandre Ghiti <alex@ghiti.fr> wrote:
>
> Hi Guo,
>
> On 30/11/2024 16:33, guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > 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: ab83647fadae ("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>
> > ---
> >   arch/riscv/kernel/jump_label.c | 12 +++++++++---
> >   1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> > index 6eee6f736f68..654ed159c830 100644
> > --- a/arch/riscv/kernel/jump_label.c
> > +++ b/arch/riscv/kernel/jump_label.c
> > @@ -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;
> >   }
>
>
> Sorry for the late answer, I've been sick lately!
I wish you a speedy recovery.

>
> Thank you very much for looking into this and finding this not-so-bad
> solution! I remind everyone that this is a temporary solution until we
> can use an alternative instead of a static key.
Herer, I want to point out that the problem is not jump_label
infrastructure but our arch_jump_label_transform_queue
->patch_insn_write. The alternative also has a similar situation. So
you still need the modification like the below:

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 467c5c735bf5..475f7c520be4 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -1017,10 +1017,17 @@ void __init_or_module
riscv_cpufeature_patch_func(struct alt_entry *begin,
                oldptr = ALT_OLD_PTR(alt);
                altptr = ALT_ALT_PTR(alt);

+if (early_boot_irqs_disabled) {
+               riscv_patch_in_stop_machine = 1;
+               patch_text_nosync(oldptr, altptr, alt->alt_len);
+               riscv_alternative_fix_offsets(oldptr, alt->alt_len,
oldptr - altptr);
+               riscv_patch_in_stop_machine = 0;
+} else {
                mutex_lock(&text_mutex);
                patch_text_nosync(oldptr, altptr, alt->alt_len);
                riscv_alternative_fix_offsets(oldptr, alt->alt_len,
oldptr - altptr);
                mutex_unlock(&text_mutex);
+}
        }
 }
 #endif

>
> You can add:
>
> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
>
> The revert is still on the table IMO, let's Palmer decide.
Okay

-- 
Best Regards
 Guo Ren

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Re: [RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[Nam Cao]

On Sat, Nov 30, 2024 at 10:33:10AM -0500, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
> 
> 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: ab83647fadae ("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: Nam Cao <namcao@linutronix.de>

Thanks for the fix,
Nam

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Re: [RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[Palmer Dabbelt]

On Wed, 04 Dec 2024 00:27:00 PST (-0800), alex@ghiti.fr wrote:
> Hi Guo,
>
> On 30/11/2024 16:33, guoren@kernel.org wrote:
>> From: Guo Ren <guoren@linux.alibaba.com>
>>
>> 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: ab83647fadae ("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>
>> ---
>>   arch/riscv/kernel/jump_label.c | 12 +++++++++---
>>   1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
>> index 6eee6f736f68..654ed159c830 100644
>> --- a/arch/riscv/kernel/jump_label.c
>> +++ b/arch/riscv/kernel/jump_label.c
>> @@ -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;
>>   }
>
>
> Sorry for the late answer, I've been sick lately!

Ya, I was also sick -- bad timing.

> Thank you very much for looking into this and finding this not-so-bad
> solution! I remind everyone that this is a temporary solution until we
> can use an alternative instead of a static key.
>
> You can add:
>
> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
>
> The revert is still on the table IMO, let's Palmer decide.

IMO it's fine to just take this as a fix.  Reverting stuff is always a 
nice big hammer to have if we don't get a fix in a reasonable timeframe, 
but with a fix avaliable in the time I was out sick anyway I think it's 
fine to just take this.

So I've got it queued up on fixes.

> Thank you again Guo, really appreciate you took the time to find this
> solution!
>
> Alex

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Re: [RESEND PATCH] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Sat, 30 Nov 2024 10:33:10 -0500 you wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
> 
> 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);
> 
> [...]

Here is the summary with links:
  - [RESEND] riscv: Fixup boot failure when CONFIG_DEBUG_RT_MUTEXES=y
    https://git.kernel.org/riscv/c/b3134b8c1a1c

You are awesome, thank you!
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