From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 07F1022A4EE for ; Tue, 24 Feb 2026 09:01:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771923719; cv=none; b=H2SEOzpTHQkGt69B7BueeG3r+TgKBV+QX056Cv6ugFeQimznzozCcahJfKGh54EiEon67Kuzg+fskHHV1oxYSy0vh++oaUqkHZfyQg3Dlcf5aFxy0NWt3qdEQCj+2Tx5aloFxLczBuEim+zaTyb4KeUk/0FenJ4rXW38GVJjY8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771923719; c=relaxed/simple; bh=Vd/GKnxZhyS6Wde3FQneQx/VqBmXBcDuRHcntPE2u2E=; h=In-Reply-To:References:From:To:Cc:Subject:MIME-Version: Content-Disposition:Content-Type:Message-Id:Date; b=TIxm9/oSPXYOElKaNtD0O/ugVNmrpsA7iieWL4Ql65+BAKu4tZbkN18oWBGAfSueUkNgW4xNP45MB0/C83RC1vlcimuwvJebiNKsENktvAxcz+q4BO5zU4155w7Cnxl4/C5Z4rl0a5p+iOjjoXaCnweOLMpZTyf5gbPXRax/E0o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=1aCWlMMJ; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="1aCWlMMJ" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Date:Sender:Message-Id:Content-Type: Content-Transfer-Encoding:MIME-Version:Subject:Cc:To:From:References: In-Reply-To:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=w0Xla7YvpmY0GVAfkZRw6ajF/x6+DgW95hZFJKTbQfA=; b=1aCWlMMJBacFbSbFPTBQdkRKLN A0dtOVoLdZA2uO+DfN02/Rl0qYJMP0hjWjHhU0cEItXKbXoWKUC7DgM3ax1RJMJEyW+Rn3BfZlASL Xdy/d9R7PuBNn74bWevkBnFX9FoV5uNMZaYh+2if5FM/pzTpZwx+zSf1zHr9mwtla3jNP55F2j5fA 75FTZwiEmVey/R7+pjgGy6b3jsgMnUH4i/9Zc3GXM2JzAzgJ+ACKuh3dTpncSIqbLoJvUPBw31qv7 MWmo/YR2si/Nb0wXQQrTyRufAV6WgBE+l+LCbYwcb3f2+KDAJc88ocDHpF6dy3PoI+k0wS7a1zTKa z6EYTX1g==; Received: from e0022681537dd.dyn.armlinux.org.uk ([fd8f:7570:feb6:1:222:68ff:fe15:37dd]:41976 helo=rmk-PC.armlinux.org.uk) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vuoIg-000000004yF-3QIo; Tue, 24 Feb 2026 09:01:50 +0000 Received: from rmk by rmk-PC.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1vuoIg-0000000Aout-0LyS; Tue, 24 Feb 2026 09:01:50 +0000 In-Reply-To: References: From: "Russell King (Oracle)" To: Andrew Lunn Cc: Alexandre Torgue , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , linux-arm-kernel@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, netdev@vger.kernel.org, Paolo Abeni Subject: [PATCH net-next v2 1/2] net: stmmac: use circ_buf helpers for descriptors Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" Message-Id: Sender: Russell King Date: Tue, 24 Feb 2026 09:01:50 +0000 The stmmac descriptor queues are circular buffers, operated as far as the hardware is concerned as either a ring, or a chain that loops back on itself. From the software perspective, it forms a circular buffer. We have a few places which calculate the number of in-use and free entries in these circular buffers, for which we have macros for. Use CIRC_CNT() and CIRC_SPACE() as appropriate to calculate these values. Validating, for stmmac_tx_avail(), which uses CIRC_SPACE(): dirty_tx = 1, cur_tx = 0 -> 0 dirty_tx = 0, cur_tx = 0 -> dma_tx_size - 1 dirty_tx = 0, cur_tx = 1 -> dma_tx_size - 2 dirty_tx passed as end, reduced by one. cur_tx passed as start. Output on sane computers is identical. For stmmac_rx_dirty(), which uses CIRC_CNT(): dirty_rx = 1, cur_rx = 0 -> dma_rx_size - 1 dirty_rx = 0, cur_rx = 0 -> 0 dirty_rx = 0, cur_rx = 1 -> 1 dirty_rx passed as start, cur_rx passed as end. Output is identical. Same validation performed on the is_last_segment calculation, which also gets converted to CIRC_CNT(). Signed-off-by: Russell King (Oracle) --- .../net/ethernet/stmicro/stmmac/stmmac_main.c | 23 ++++++------------- 1 file changed, 7 insertions(+), 16 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index a2a0985e8c37..2d74fe98ad61 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -14,6 +14,7 @@ https://bugzilla.stlinux.com/ *******************************************************************************/ +#include #include #include #include @@ -355,14 +356,9 @@ static void print_pkt(unsigned char *buf, int len) static inline u32 stmmac_tx_avail(struct stmmac_priv *priv, u32 queue) { struct stmmac_tx_queue *tx_q = &priv->dma_conf.tx_queue[queue]; - u32 avail; - if (tx_q->dirty_tx > tx_q->cur_tx) - avail = tx_q->dirty_tx - tx_q->cur_tx - 1; - else - avail = priv->dma_conf.dma_tx_size - tx_q->cur_tx + tx_q->dirty_tx - 1; - - return avail; + return CIRC_SPACE(tx_q->cur_tx, tx_q->dirty_tx, + priv->dma_conf.dma_tx_size); } /** @@ -373,14 +369,9 @@ static inline u32 stmmac_tx_avail(struct stmmac_priv *priv, u32 queue) static inline u32 stmmac_rx_dirty(struct stmmac_priv *priv, u32 queue) { struct stmmac_rx_queue *rx_q = &priv->dma_conf.rx_queue[queue]; - u32 dirty; - - if (rx_q->dirty_rx <= rx_q->cur_rx) - dirty = rx_q->cur_rx - rx_q->dirty_rx; - else - dirty = priv->dma_conf.dma_rx_size - rx_q->dirty_rx + rx_q->cur_rx; - return dirty; + return CIRC_CNT(rx_q->cur_rx, rx_q->dirty_rx, + priv->dma_conf.dma_rx_size); } static bool stmmac_eee_tx_busy(struct stmmac_priv *priv) @@ -4571,8 +4562,8 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev) /* If we only have one entry used, then the first entry is the last * segment. */ - is_last_segment = ((tx_q->cur_tx - first_entry) & - (priv->dma_conf.dma_tx_size - 1)) == 1; + is_last_segment = CIRC_CNT(tx_q->cur_tx, first_entry, + priv->dma_conf.dma_tx_size) == 1; /* Complete the first descriptor before granting the DMA */ stmmac_prepare_tso_tx_desc(priv, first, 1, proto_hdr_len, 0, 1, -- 2.47.3