netdev - [PATCH] net: ethernet: ti: davinci_cpdma: fix warning "device driver frees DMA memory with different size"

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Date:   Wed, 4 Dec 2019 14:46:18 +0200
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
CC:     Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        Grygorii Strashko <grygorii.strashko@...com>
Subject: [PATCH] net: ethernet: ti: davinci_cpdma: fix warning "device driver frees DMA memory with different size"

The TI CPSW(s) driver produces warning with DMA API debug options enabled:

WARNING: CPU: 0 PID: 1033 at kernel/dma/debug.c:1025 check_unmap+0x4a8/0x968
DMA-API: cpsw 48484000.ethernet: device driver frees DMA memory with different size
 [device address=0x00000000abc6aa02] [map size=64 bytes] [unmap size=42 bytes]
CPU: 0 PID: 1033 Comm: ping Not tainted 5.3.0-dirty #41
Hardware name: Generic DRA72X (Flattened Device Tree)
[<c0112c60>] (unwind_backtrace) from [<c010d270>] (show_stack+0x10/0x14)
[<c010d270>] (show_stack) from [<c09bc564>] (dump_stack+0xd8/0x110)
[<c09bc564>] (dump_stack) from [<c013b93c>] (__warn+0xe0/0x10c)
[<c013b93c>] (__warn) from [<c013b9ac>] (warn_slowpath_fmt+0x44/0x6c)
[<c013b9ac>] (warn_slowpath_fmt) from [<c01e0368>] (check_unmap+0x4a8/0x968)
[<c01e0368>] (check_unmap) from [<c01e08a8>] (debug_dma_unmap_page+0x80/0x90)
[<c01e08a8>] (debug_dma_unmap_page) from [<c0752414>] (__cpdma_chan_free+0x114/0x16c)
[<c0752414>] (__cpdma_chan_free) from [<c07525c4>] (__cpdma_chan_process+0x158/0x17c)
[<c07525c4>] (__cpdma_chan_process) from [<c0753690>] (cpdma_chan_process+0x3c/0x5c)
[<c0753690>] (cpdma_chan_process) from [<c0758660>] (cpsw_tx_mq_poll+0x48/0x94)
[<c0758660>] (cpsw_tx_mq_poll) from [<c0803018>] (net_rx_action+0x108/0x4e4)
[<c0803018>] (net_rx_action) from [<c010230c>] (__do_softirq+0xec/0x598)
[<c010230c>] (__do_softirq) from [<c0143914>] (do_softirq.part.4+0x68/0x74)
[<c0143914>] (do_softirq.part.4) from [<c0143a44>] (__local_bh_enable_ip+0x124/0x17c)
[<c0143a44>] (__local_bh_enable_ip) from [<c0871590>] (ip_finish_output2+0x294/0xb7c)
[<c0871590>] (ip_finish_output2) from [<c0875440>] (ip_output+0x210/0x364)
[<c0875440>] (ip_output) from [<c0875e2c>] (ip_send_skb+0x1c/0xf8)
[<c0875e2c>] (ip_send_skb) from [<c08a7fd4>] (raw_sendmsg+0x9a8/0xc74)
[<c08a7fd4>] (raw_sendmsg) from [<c07d6b90>] (sock_sendmsg+0x14/0x24)
[<c07d6b90>] (sock_sendmsg) from [<c07d8260>] (__sys_sendto+0xbc/0x100)
[<c07d8260>] (__sys_sendto) from [<c01011ac>] (__sys_trace_return+0x0/0x14)
Exception stack(0xea9a7fa8 to 0xea9a7ff0)
...

The reason is that cpdma_chan_submit_si() now stores original buffer length
(sw_len) in CPDMA descriptor instead of adjusted buffer length (hw_len)
used to map the buffer.

Hence, fix an issue by using adjusted buffer length (hw_len) to unmap
packet buffer.

Cc: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
Fixes: 6670acacd59e ("net: ethernet: ti: davinci_cpdma: add dma mapped submit")
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
 drivers/net/ethernet/ti/davinci_cpdma.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
index 37ba708ac781..6be5a514d5b1 100644
--- a/drivers/net/ethernet/ti/davinci_cpdma.c
+++ b/drivers/net/ethernet/ti/davinci_cpdma.c
@@ -1197,12 +1197,13 @@ static void __cpdma_chan_free(struct cpdma_chan *chan,
 {
 	struct cpdma_ctlr		*ctlr = chan->ctlr;
 	struct cpdma_desc_pool		*pool = ctlr->pool;
+	int				origlen, hw_len;
 	dma_addr_t			buff_dma;
-	int				origlen;
 	uintptr_t			token;
 
 	token      = desc_read(desc, sw_token);
 	origlen    = desc_read(desc, sw_len);
+	hw_len = desc_read(desc, hw_len);
 
 	buff_dma   = desc_read(desc, sw_buffer);
 	if (origlen & CPDMA_DMA_EXT_MAP) {
@@ -1210,7 +1211,7 @@ static void __cpdma_chan_free(struct cpdma_chan *chan,
 		dma_sync_single_for_cpu(ctlr->dev, buff_dma, origlen,
 					chan->dir);
 	} else {
-		dma_unmap_single(ctlr->dev, buff_dma, origlen, chan->dir);
+		dma_unmap_single(ctlr->dev, buff_dma, hw_len, chan->dir);
 	}
 
 	cpdma_desc_free(pool, desc, 1);
-- 
2.17.1