From: Jason Gunthorpe <jgg@ziepe.ca>
To: Ginger <ginger.jzllee@gmail.com>
Cc: Tariq Toukan <tariqt@nvidia.com>,
netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
ttoukan.linux@gmail.com
Subject: Re: [bug report] Potential refcounting
Date: Wed, 29 Apr 2026 09:44:51 -0300 [thread overview]
Message-ID: <20260429124451.GN849557@ziepe.ca> (raw)
In-Reply-To: <CAGp+u1baSuC9z9rGkJR0v1+eBW==9ppxh7tSn19jJOA9bX1Ycg@mail.gmail.com>
On Wed, Apr 29, 2026 at 06:13:40PM +0800, Ginger wrote:
> Side note: to see if T1 (i.e., IRQ) can fire, I checked the calling
> path to 'mlx4_cq_free' and only 'synchronize_irq()' is seen, but not
> 'disable_irq()'. It means that T1 may still happen after T0 calls
> 'mlx4_cq_free()'.
synchronize_irq() is supposed to wait for any concurrently running IRQ
threads to finish. New IRQ threads will then be guarenteed to see the
radix_tree_delete() and can't see the CQ being removed here.
Since the refcount is != 0 until after synchronize_irq(), and the irq
can't see the cq after synchronize_irq() there should be no issue.
Jason
prev parent reply other threads:[~2026-04-29 12:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 2:07 [bug report] Potential refcounting Ginger
2026-04-29 8:36 ` Tariq Toukan
2026-04-29 10:13 ` Ginger
2026-04-29 12:44 ` Jason Gunthorpe [this message]
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