Re: [PATCH net] amd-xgbe: Fix race between access of desc and desc index
From: Tom LendackyDate: Wed, 28 Oct 2015 08:48:36 -0500 > On 10/27/2015 09:50 PM, David Miller wrote: >> From: Tom Lendacky >> Date: Mon, 26 Oct 2015 17:13:54 -0500 >> >>> During Tx cleanup it's still possible for the descriptor data to be >>> read ahead of the descriptor index. A memory barrier is required >>> between >>> the read of the descriptor index and the start of the Tx cleanup loop. >>> This allows a change to a lighter-weight barrier in the Tx transmit >>> routine just before updating the current descriptor index. >>> >>> Since the memory barrier does result in extra overhead on arm64, keep >>> the previous change to not chase the current descriptor value. This >>> prevents the execution of the barrier for each loop performed. >>> >>> Suggested-by: Alexander Duyck >>> Signed-off-by: Tom Lendacky >> >> Applied, thanks. >> > > Thanks David. Could you queue this up for the 4.1 and 4.2 stable > trees? Ok, done. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH net] amd-xgbe: Fix race between access of desc and desc index
On 10/27/2015 09:50 PM, David Miller wrote: From: Tom LendackyDate: Mon, 26 Oct 2015 17:13:54 -0500 During Tx cleanup it's still possible for the descriptor data to be read ahead of the descriptor index. A memory barrier is required between the read of the descriptor index and the start of the Tx cleanup loop. This allows a change to a lighter-weight barrier in the Tx transmit routine just before updating the current descriptor index. Since the memory barrier does result in extra overhead on arm64, keep the previous change to not chase the current descriptor value. This prevents the execution of the barrier for each loop performed. Suggested-by: Alexander Duyck Signed-off-by: Tom Lendacky Applied, thanks. Thanks David. Could you queue this up for the 4.1 and 4.2 stable trees? Thanks, Tom -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH net] amd-xgbe: Fix race between access of desc and desc index
From: Tom LendackyDate: Mon, 26 Oct 2015 17:13:54 -0500 > During Tx cleanup it's still possible for the descriptor data to be > read ahead of the descriptor index. A memory barrier is required between > the read of the descriptor index and the start of the Tx cleanup loop. > This allows a change to a lighter-weight barrier in the Tx transmit > routine just before updating the current descriptor index. > > Since the memory barrier does result in extra overhead on arm64, keep > the previous change to not chase the current descriptor value. This > prevents the execution of the barrier for each loop performed. > > Suggested-by: Alexander Duyck > Signed-off-by: Tom Lendacky Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html