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[34.85.235.172]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-65c7af99a95sm1524615d50.12.2026.05.06.12.31.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 May 2026 12:31:49 -0700 (PDT) Date: Wed, 06 May 2026 15:31:49 -0400 From: Willem de Bruijn To: Daniel Zahka , Jakub Kicinski , Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , Willem de Bruijn , Willem de Bruijn Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: In-Reply-To: <20260505-psd-rcu-v1-2-a8f69ec1ab96@gmail.com> References: <20260505-psd-rcu-v1-0-a8f69ec1ab96@gmail.com> <20260505-psd-rcu-v1-2-a8f69ec1ab96@gmail.com> Subject: Re: [PATCH net 2/3] netdevsim: psp: serialize calls to nsim_psp_uninit() Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Daniel Zahka wrote: > The debugfs write handler, nsim_psp_rereg_write(), can race against > nsim_destroy() and against itself, causing nsim_psp_uninit() to run > more than once concurrently. Two complementary changes serialize all > callers: nit: sounds and looks as if this would be simpler as two patches. but no need to respin just for that. > > 1. Delete the psp_rereg debugfs file from nsim_psp_uninit() before > doing the actual teardown. debugfs_remove() drains any in-flight > writers and prevents new ones from starting. > > 2. Add a mutex around the body of nsim_psp_rereg_write() so that two > concurrent userspace writers cannot both enter the teardown path > at once. > > The teardown work itself is moved into a new __nsim_psp_uninit() that > the rereg handler calls under the mutex, while the public > nsim_psp_uninit() wraps it with the debugfs_remove()/mutex_destroy() > pair so nsim_destroy() doesn't have to know about the psp internals. > > Fixes: f857478d6206 ("netdevsim: a basic test PSP implementation") > Assisted-by: Claude:claude-opus-4.6 > Signed-off-by: Daniel Zahka Reviewed-by: Willem de Bruijn