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[37.145.186.126]) by smtp.gmail.com with ESMTPSA id x4sm2407822ljj.62.2020.10.10.08.53.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 10 Oct 2020 08:53:34 -0700 (PDT) Message-ID: Subject: Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame From: Elena Afanasova To: David Gibson Date: Sat, 10 Oct 2020 08:53:00 -0700 In-Reply-To: <20201010060745.GK1025389@yekko.fritz.box> References: <8f07132478469b35fb50a4706691e2b56b10a67b.camel@gmail.com> <20201010060745.GK1025389@yekko.fritz.box> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2a00:1450:4864:20::143; envelope-from=eafanasova@gmail.com; helo=mail-lf1-x143.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-trivial@nongnu.org, jasowang@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sat, 2020-10-10 at 17:07 +1100, David Gibson wrote: > On Fri, Oct 09, 2020 at 07:02:56AM -0700, Elena Afanasova wrote: > > > From 09905773a00e417d3a37c12350d9e55466fdce8a Mon Sep 17 00:00:00 > > > 2001 > > From: Elena Afanasova > > Date: Fri, 9 Oct 2020 06:41:36 -0700 > > Subject: [PATCH] hw/net: move allocation to the heap due to very > > large stack > > frame > > Patch looks fine, but some more details of the motivation would be > nice. I wouldn't have thought that the size of a network packet > counted as a "very large" stack frame by userspace standards. > gcc with wstack-usage warns that stack frame size may be ~65Kbytes > > Signed-off-by: Elena Afanasova > > --- > > hw/net/spapr_llan.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/hw/net/spapr_llan.c b/hw/net/spapr_llan.c > > index 2093f1bad0..581320a0e7 100644 > > --- a/hw/net/spapr_llan.c > > +++ b/hw/net/spapr_llan.c > > @@ -688,7 +688,8 @@ static target_ulong > > h_send_logical_lan(PowerPCCPU *cpu, > > SpaprVioDevice *sdev = spapr_vio_find_by_reg(spapr->vio_bus, > > reg); > > SpaprVioVlan *dev = VIO_SPAPR_VLAN_DEVICE(sdev); > > unsigned total_len; > > - uint8_t *lbuf, *p; > > + uint8_t *p; > > + g_autofree uint8_t *lbuf = NULL; > > int i, nbufs; > > int ret; > > > > @@ -729,7 +730,7 @@ static target_ulong > > h_send_logical_lan(PowerPCCPU *cpu, > > return H_RESOURCE; > > } > > > > - lbuf = alloca(total_len); > > + lbuf = g_malloc(total_len); > > p = lbuf; > > for (i = 0; i < nbufs; i++) { > > ret = spapr_vio_dma_read(sdev, VLAN_BD_ADDR(bufs[i]),