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From: Ming Lei <ming.lei@redhat.com>
To: Uday Shankar <ushankar@purestorage.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	Caleb Sander Mateos <csander@purestorage.com>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] ublk: introduce and use ublk_set_canceling helper
Date: Fri, 4 Jul 2025 20:36:01 +0800	[thread overview]
Message-ID: <aGfKsZgztW53svl-@fedora> (raw)
In-Reply-To: <20250703-ublk_too_many_quiesce-v2-2-3527b5339eeb@purestorage.com>

On Thu, Jul 03, 2025 at 11:41:08PM -0600, Uday Shankar wrote:
> For performance reasons (minimizing the number of cache lines accessed
> in the hot path), we store the "canceling" state redundantly - there is
> one flag in the device, which can be considered the source of truth, and
> per-queue copies of that flag. This redundancy can cause confusion, and
> opens the door to bugs where the state is set inconsistently. Try to
> guard against these bugs by introducing a ublk_set_canceling helper
> which is the sole mutator of both the per-device and per-queue canceling
> state. This helper always sets the state consistently. Use the helper in
> all places where we need to modify the canceling state.
> 
> No functional changes are expected.
> 
> Signed-off-by: Uday Shankar <ushankar@purestorage.com>

Reviewed-by: Ming Lei <ming.lei@redhat.com>

thanks,
Ming


  reply	other threads:[~2025-07-04 12:36 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-04  5:41 [PATCH v2 0/2] ublk: speed up ublk server exit handling Uday Shankar
2025-07-04  5:41 ` [PATCH v2 1/2] " Uday Shankar
2025-07-04 12:35   ` Ming Lei
2025-07-04 13:21   ` Caleb Sander Mateos
2025-07-04  5:41 ` [PATCH v2 2/2] ublk: introduce and use ublk_set_canceling helper Uday Shankar
2025-07-04 12:36   ` Ming Lei [this message]
2025-07-04 13:30   ` Caleb Sander Mateos
2025-07-04 15:31 ` [PATCH v2 0/2] ublk: speed up ublk server exit handling Jens Axboe

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