From: Christoph Hellwig <hch@lst.de>
To: Nilay Shroff <nilay@linux.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>,
linux-block@vger.kernel.org, ming.lei@redhat.com,
axboe@kernel.dk, sth@linux.ibm.com, gjoyce@ibm.com
Subject: Re: [PATCHv3 2/2] block: fix lock dependency between percpu alloc lock and elevator lock
Date: Mon, 23 Jun 2025 15:36:48 +0200 [thread overview]
Message-ID: <20250623133648.GB27271@lst.de> (raw)
In-Reply-To: <f306f309-7cc2-4426-98bf-fb6684db5b7c@linux.ibm.com>
On Mon, Jun 23, 2025 at 03:03:27PM +0530, Nilay Shroff wrote:
> >
> > This is a check for not having an elevator so far, right? Wouldn't
> > !q->elevator be the more obvious check for that? Or am I missing
> > something why that's not safe here?
> >
> This code runs in the context of an elevator switch, not as part of an
> nr_hw_queues update. Hence, at this point, q->elevator has not yet been
> updated to the new elevator we’re switching to, so accessing q->elevator
> here would be incorrect. Since we've already stored the name of the target
> elevator in ctx->name, we use that instead of referencing q->elevator here.
Make sense, thanks.
prev parent reply other threads:[~2025-06-23 13:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-16 17:32 [PATCHv3 0/2] block: move sched_tags allocation/de-allocation outside of locking context Nilay Shroff
2025-06-16 17:32 ` [PATCHv3 1/2] block: move elevator queue allocation logic into blk_mq_init_sched Nilay Shroff
2025-06-17 15:07 ` Ming Lei
2025-06-20 14:39 ` Nilay Shroff
2025-06-20 15:17 ` Ming Lei
2025-06-20 16:13 ` Nilay Shroff
2025-06-23 5:56 ` Christoph Hellwig
2025-06-23 9:14 ` Nilay Shroff
2025-06-16 17:32 ` [PATCHv3 2/2] block: fix lock dependency between percpu alloc lock and elevator lock Nilay Shroff
2025-06-18 3:06 ` Ming Lei
2025-06-18 6:52 ` Nilay Shroff
2025-06-23 6:10 ` Christoph Hellwig
2025-06-23 9:33 ` Nilay Shroff
2025-06-23 13:36 ` Christoph Hellwig [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250623133648.GB27271@lst.de \
--to=hch@lst.de \
--cc=axboe@kernel.dk \
--cc=gjoyce@ibm.com \
--cc=linux-block@vger.kernel.org \
--cc=ming.lei@redhat.com \
--cc=nilay@linux.ibm.com \
--cc=sth@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox