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[70.114.247.242]) by smtp.gmail.com with ESMTPSA id b10sm2452246oti.61.2019.08.16.12.27.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Aug 2019 12:27:12 -0700 (PDT) From: Denis Kenzior To: linux-wireless@vger.kernel.org, johannes@sipsolutions.net Cc: Denis Kenzior Subject: [RFCv2 3/4] nl80211: Don't split-dump for clients with large buffers Date: Fri, 16 Aug 2019 14:27:02 -0500 Message-Id: <20190816192703.12445-3-denkenz@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190816192703.12445-1-denkenz@gmail.com> References: <20190816192703.12445-1-denkenz@gmail.com> MIME-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Signed-off-by: Denis Kenzior --- net/wireless/nl80211.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 682a095415eb..24b67de99f3a 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -2498,6 +2498,22 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb) rtnl_unlock(); return ret; } + + /* + * auto-detect support for large buffer sizes: af_netlink + * will allocate skbufs larger than 4096 in cases where + * it detects that the client receive buffer (given to + * recvmsg) is bigger. In such cases we can assume that + * performing split dumps is wasteful since the client + * can likely safely consume the entire un-split wiphy + * message in one go without the extra message header + * overhead. + */ + if (skb_tailroom(skb) > 4096) { + state->large_message = true; + state->split = false; + } + cb->args[0] = (long)state; } @@ -2531,6 +2547,7 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb) * We can then retry with the larger buffer. */ if ((ret == -ENOBUFS || ret == -EMSGSIZE) && + !state->large_message && !skb->len && !state->split && cb->min_dump_alloc < 4096) { cb->min_dump_alloc = 4096;