linux-kernel - [PATCH net 1/4] net: mvpp2: fix the txq

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Message-Id: <20171128131951.25383-2-antoine.tenart@free-electrons.com>
Date:   Tue, 28 Nov 2017 14:19:48 +0100
From:   Antoine Tenart <antoine.tenart@...e-electrons.com>
To:     davem@...emloft.net
Cc:     Antoine Tenart <antoine.tenart@...e-electrons.com>,
        gregory.clement@...e-electrons.com,
        thomas.petazzoni@...e-electrons.com,
        miquel.raynal@...e-electrons.com, nadavh@...vell.com,
        mw@...ihalf.com, stefanc@...vell.com, ymarkman@...vell.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net 1/4] net: mvpp2: fix the txq_init error path

When an allocation in the txq_init path fails, the allocated buffers
end-up being freed twice: in the txq_init error path, and in txq_deinit.
This lead to issues as txq_deinit would work on already freed memory
regions:

    kernel BUG at mm/slub.c:3915!
    Internal error: Oops - BUG: 0 [#1] PREEMPT SMP

This patch fixes this by removing the txq_init own error path, as the
txq_deinit function is always called on errors. This was introduced by
TSO as way more buffers are allocated.

Fixes: 186cd4d4e414 ("net: mvpp2: software tso support")
Signed-off-by: Antoine Tenart <antoine.tenart@...e-electrons.com>
---
 drivers/net/ethernet/marvell/mvpp2.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2.c b/drivers/net/ethernet/marvell/mvpp2.c
index 6c20e811f973..79f01cd80dd7 100644
--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -5805,7 +5805,7 @@ static int mvpp2_txq_init(struct mvpp2_port *port,
 						sizeof(*txq_pcpu->buffs),
 						GFP_KERNEL);
 		if (!txq_pcpu->buffs)
-			goto cleanup;
+			return -ENOMEM;
 
 		txq_pcpu->count = 0;
 		txq_pcpu->reserved_num = 0;
@@ -5821,26 +5821,10 @@ static int mvpp2_txq_init(struct mvpp2_port *port,
 					   &txq_pcpu->tso_headers_dma,
 					   GFP_KERNEL);
 		if (!txq_pcpu->tso_headers)
-			goto cleanup;
+			return -ENOMEM;
 	}
 
 	return 0;
-cleanup:
-	for_each_present_cpu(cpu) {
-		txq_pcpu = per_cpu_ptr(txq->pcpu, cpu);
-		kfree(txq_pcpu->buffs);
-
-		dma_free_coherent(port->dev->dev.parent,
-				  txq_pcpu->size * TSO_HEADER_SIZE,
-				  txq_pcpu->tso_headers,
-				  txq_pcpu->tso_headers_dma);
-	}
-
-	dma_free_coherent(port->dev->dev.parent,
-			  txq->size * MVPP2_DESC_ALIGNED_SIZE,
-			  txq->descs, txq->descs_dma);
-
-	return -ENOMEM;
 }
 
 /* Free allocated TXQ resources */
-- 
2.14.3