Re: [PATCH v2 1/4] seqlock: introduce scoped_seqlock_read() and scoped_seqlock_read_irqsave()

[Peter Zijlstra]

On Wed, Oct 08, 2025 at 02:30:45PM +0200, Oleg Nesterov wrote:
> The read_seqbegin/need_seqretry/done_seqretry API is cumbersome and
> error prone. With the new helper the "typical" code like
> 
> 	int seq, nextseq;
> 	unsigned long flags;
> 
> 	nextseq = 0;
> 	do {
> 		seq = nextseq;
> 		flags = read_seqbegin_or_lock_irqsave(&seqlock, &seq);
> 
> 		// read-side critical section
> 
> 		nextseq = 1;
> 	} while (need_seqretry(&seqlock, seq));
> 	done_seqretry_irqrestore(&seqlock, seq, flags);
> 
> can be rewritten as
> 
> 	scoped_seqlock_read_irqsave (&seqlock) {
> 		// read-side critical section
> 	}
> 

Hmm, on first reading I was expecting that to be:

	do {
		seq = read_seqbegin(&seqlock);

		// read-side section

	} while (read_seqretry(&seqlock, seq));

for lack of that _or_lock() wording, but I suppose we can make that
something like:

 	scoped_seqbegin_read (&seqlock) {
		// read-side section
	}

which is distinctive enough.