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[209.93.1.190]) by smtp.gmail.com with ESMTPSA id v16sm4653321wrr.6.2021.06.10.12.53.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Jun 2021 12:53:11 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.100.0.2.22\)) Subject: Re: [PATCH] function mana_hwc_create_wq leaks memory From: Dhiraj Shah In-Reply-To: Date: Thu, 10 Jun 2021 20:53:10 +0100 Cc: KY Srinivasan , Haiyang Zhang , Stephen Hemminger , Wei Liu , "David S. Miller" , Jakub Kicinski , Shachar Raindel , Colin Ian King , "linux-hyperv@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Transfer-Encoding: quoted-printable Message-Id: <98DC11D9-668E-47F2-891C-6F41E70BD5F4@gmail.com> References: <20210610152925.18145-1-find.dhiraj@gmail.com> To: Dexuan Cui X-Mailer: Apple Mail (2.3654.100.0.2.22) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dexuan, Thanks for the feedback. You are right saying =E2=80=98mana_hwc_destroy_wq' free=E2=80=99s up the = queue.=20 However for example if function 'mana_hwc_alloc_dma_buf' fails it will = goto =E2=80=98out' and call =E2=80=98mana_hwc_destroy_wq', the value = 'hwc_wq->gdma_wq' is still not assigned at this point. In the = =E2=80=98mana_hwc_destroy_wq' function i see it checks for = 'hwc_wq->gdma_wq' before calling, =E2=80=98mana_gd_destroy_queue', which = makes me think queue is still not freed. Please let me know if i am missing something. Regards, /Dhiraj > On 10 Jun 2021, at 18:28, Dexuan Cui wrote: >=20 >> From: Dexuan Cui >> Sent: Thursday, June 10, 2021 10:18 AM >> ... >>> diff --git a/drivers/net/ethernet/microsoft/mana/hw_channel.c >>> b/drivers/net/ethernet/microsoft/mana/hw_channel.c >>> index 1a923fd99990..4aa4bda518fb 100644 >>> --- a/drivers/net/ethernet/microsoft/mana/hw_channel.c >>> +++ b/drivers/net/ethernet/microsoft/mana/hw_channel.c >>> @@ -501,8 +501,10 @@ static int mana_hwc_create_wq(struct >>> hw_channel_context *hwc, >>> *hwc_wq_ptr =3D hwc_wq; >>> return 0; >>> out: >>> - if (err) >>> + if (err) { >>=20 >> Here the 'err' must be non-zero. Can you please remove this 'if'? >>=20 >>> + kfree(queue); >>> mana_hwc_destroy_wq(hwc, hwc_wq); >>> + } >>> return err; >>> } >>=20 >> Reviewed-by: Dexuan Cui >=20 > Hi Dhiraj, > I checked the code again and it looks like your patch is actually > unnecessary as IMO there is no memory leak here: the 'queue' > pointer is passed to mana_hwc_destroy_wq() as hwc_wq->gdma_wq, > and is later freed in mana_gd_destroy_queue() -> > mana_gd_destroy_queue(). >=20 > The 'if' test can be removed as the 'err's is always non-zero there. >=20 > Thanks, > Dexuan