Re: [PATCH] lock: Add doc comments for spin_lock_irq()
From: Waiman Long
Date: Sat Oct 11 2025 - 22:31:22 EST
On 10/11/25 2:28 PM, Daroc Alden wrote:
On Fri, 10 Oct 2025 23:15:50 -0400
Waiman Long <llong@xxxxxxxxxx> wrote:
On 10/10/25 5:53 PM, Daroc Alden wrote:Because I had to research spin_lock_irq()/spin_lock_irqsave() for a
The commonly used spin_lock_irq(), spin_lock_irqsave(),This patch looks fine. Just wonder why just
spin_unlock_irq(), and spin_unlock_irqrestore() functions do not
currently have any documentation; this commit adds kerneldoc
comments to these four functions describing when their behavior and
when they are appropriate to use.
Signed-off-by: Daroc Alden <daroc@xxxxxxx>
spin_lock_irq()/spin_lock_irqsave() and not
spin_lock()/spin_lock_bh() as these functions also don't have
kerneldoc comments. Also spin_lock_irqsave() is a macro and not
actually a function, maybe we should mention that in the comment.
recent article, and therefore felt confident that I understood how they
behaved and what should go in the doc comment.
If you — as a more experienced kernel person — can describe how/why the
_bh() variants are used, I'm happy to add doc comments for them as
well. My current understanding is that they interact with whatever is
left of the "big kernel lock". Is that right?
"bh" in spin_lock_bh() stands for bottom half which is essentially what what is being done in the softIRQ context. So spin_lock_bh() just prevents the softIRQ code from being executed. This is my understanding, but I may have missed other use cases of spin_lock_bh(). Others can chime in if there is more to say. Anyway, I am fine with adding more comments to spinlock code.
Cheers, Longman