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Thu, 30 Jul 2026 09:21:41 -0700 (PDT) Received: from Potato.tail66a299.ts.net ([171.76.83.76]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13e7275973dsm19964269c88.15.2026.07.30.09.21.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2026 09:21:41 -0700 (PDT) From: Shivesh X-Google-Original-From: Shivesh To: arend.vanspriel@broadcom.com Cc: linux-wireless@vger.kernel.org, brcm80211@lists.linux.dev, brcm80211-dev-list.pdl@broadcom.com, linux-kernel@vger.kernel.org, Shivesh Subject: [PATCH v2 1/8] wifi: brcmfmac: flowring: replace O(N) loop with atomic counter Date: Thu, 30 Jul 2026 16:21:04 +0000 Message-ID: <20260730162135.12278-1-shivesh@example.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Shivesh Optimizes flowring deletion by tracking counter updates with a flag instead of an O(N) spinlock walk, fixing a teardown leak. Signed-off-by: Shivesh --- .../broadcom/brcm80211/brcmfmac/flowring.c | 65 ++++++++++++++----- .../broadcom/brcm80211/brcmfmac/flowring.h | 18 +++++ 2 files changed, 66 insertions(+), 17 deletions(-) diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.c index 35cbcea0abc9..b9c518939f50 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.c @@ -182,10 +182,8 @@ static void brcmf_flowring_block(struct brcmf_flowring *flow, u16 flowid, struct brcmf_bus *bus_if; struct brcmf_pub *drvr; struct brcmf_if *ifp; - bool currently_blocked; - int i; - u8 ifidx; unsigned long flags; + u8 ifidx; spin_lock_irqsave(&flow->block_lock, flags); @@ -194,23 +192,54 @@ static void brcmf_flowring_block(struct brcmf_flowring *flow, u16 flowid, spin_unlock_irqrestore(&flow->block_lock, flags); return; } - ifidx = brcmf_flowring_ifidx_get(flow, flowid); - currently_blocked = false; - for (i = 0; i < flow->nrofrings; i++) { - if ((flow->rings[i]) && (i != flowid)) { - ring = flow->rings[i]; - if ((ring->status == RING_OPEN) && - (brcmf_flowring_ifidx_get(flow, i) == ifidx)) { - if (ring->blocked) { - currently_blocked = true; - break; - } - } + ifidx = brcmf_flowring_ifidx_get(flow, flowid); + ring->blocked = blocked; + + /* + * Maintain the per-interface blocked-ring counter. + * + * We use ring->counted_in_blocked rather than checking + * ring->status here. A ring that became blocked while + * RING_OPEN has already been counted (counted_in_blocked=true). + * By the time we unblock it during teardown its status may have + * advanced to RING_CLOSING, so testing RING_OPEN would wrongly + * skip the atomic_dec and permanently leak the counter, leaving + * the netif queue stopped forever. + * + * Rule: + * block transition (unblocked→blocked): count only if RING_OPEN, + * set counted_in_blocked. + * unblock transition (blocked→unblocked): decrement only if we + * previously counted it, + * clear counted_in_blocked. + */ + if (blocked) { + if (ring->status == RING_OPEN) { + atomic_inc(&flow->if_blocked_cnt[ifidx]); + ring->counted_in_blocked = true; } + } else { + if (ring->counted_in_blocked) { + atomic_dec(&flow->if_blocked_cnt[ifidx]); + ring->counted_in_blocked = false; + } + } + + /* + * Only propagate a netif queue-stop/wake when the interface + * transitions between fully-clear and at-least-one-blocked. + * Reading the atomic is safe here: we hold block_lock, so no + * concurrent brcmf_flowring_block() call can race the update + * we just made above. + */ + if (blocked && atomic_read(&flow->if_blocked_cnt[ifidx]) != 1) { + /* Another ring was already blocked; no new queue-stop needed. */ + spin_unlock_irqrestore(&flow->block_lock, flags); + return; } - flow->rings[flowid]->blocked = blocked; - if (currently_blocked) { + if (!blocked && atomic_read(&flow->if_blocked_cnt[ifidx]) != 0) { + /* More rings still blocked; do not wake the queue yet. */ spin_unlock_irqrestore(&flow->block_lock, flags); return; } @@ -367,6 +396,8 @@ struct brcmf_flowring *brcmf_flowring_attach(struct device *dev, u16 nrofrings) spin_lock_init(&flow->block_lock); for (i = 0; i < ARRAY_SIZE(flow->addr_mode); i++) flow->addr_mode[i] = ADDR_INDIRECT; + for (i = 0; i < ARRAY_SIZE(flow->if_blocked_cnt); i++) + atomic_set(&flow->if_blocked_cnt[i], 0); for (i = 0; i < ARRAY_SIZE(flow->hash); i++) flow->hash[i].ifidx = BRCMF_FLOWRING_INVALID_IFIDX; } diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.h index f3d511f9a3c9..afdea8b3f8aa 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.h +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/flowring.h @@ -5,6 +5,8 @@ #ifndef BRCMFMAC_FLOWRING_H #define BRCMFMAC_FLOWRING_H +#include + #define BRCMF_FLOWRING_HASHSIZE 512 /* has to be 2^x */ #define BRCMF_FLOWRING_INVALID_ID 0xFFFFFFFF @@ -26,6 +28,16 @@ enum ring_status { struct brcmf_flowring_ring { u16 hash_id; bool blocked; + /* + * True when this ring has been counted in the per-interface + * if_blocked_cnt[]. Set to true whenever the ring transitions + * unblocked→blocked while RING_OPEN; cleared on the matching + * blocked→unblocked transition. Needed so that a ring that + * becomes blocked while RING_OPEN and is later moved to + * RING_CLOSING still correctly decrements the counter at + * teardown, even though its status is no longer RING_OPEN. + */ + bool counted_in_blocked; enum ring_status status; struct sk_buff_head skblist; }; @@ -40,6 +52,12 @@ struct brcmf_flowring { struct brcmf_flowring_hash hash[BRCMF_FLOWRING_HASHSIZE]; spinlock_t block_lock; enum proto_addr_mode addr_mode[BRCMF_MAX_IFS]; + /* Per-interface count of currently blocked open rings. + * Maintained atomically so brcmf_flowring_block() can check + * whether any sibling ring is already blocked in O(1) without + * holding block_lock across an O(nrofrings) walk. + */ + atomic_t if_blocked_cnt[BRCMF_MAX_IFS]; u16 nrofrings; bool tdls_active; struct brcmf_flowring_tdls_entry *tdls_entry; -- 2.53.0