Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934005AbbHJKQo (ORCPT ); Mon, 10 Aug 2015 06:16:44 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43965 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933909AbbHJKQW (ORCPT ); Mon, 10 Aug 2015 06:16:22 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Lior Amsalem" , "Vinod Koul" , "Ofer Heifetz" , "Maxime Ripard" Date: Mon, 10 Aug 2015 12:12:30 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 027/110] dmaengine: mv_xor: bug fix for racing condition in descriptors cleanup In-Reply-To: X-SA-Exim-Connect-IP: 2.173.94.72 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4286 Lines: 139 3.2.71-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Lior Amsalem commit 9136291f1dbc1d4d1cacd2840fb35f4f3ce16c46 upstream. This patch fixes a bug in the XOR driver where the cleanup function can be called and free descriptors that never been processed by the engine (which result in data errors). The cleanup function will free descriptors based on the ownership bit in the descriptors. Fixes: ff7b04796d98 ("dmaengine: DMA engine driver for Marvell XOR engine") Signed-off-by: Lior Amsalem Signed-off-by: Maxime Ripard Reviewed-by: Ofer Heifetz Signed-off-by: Vinod Koul [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- drivers/dma/mv_xor.c | 72 +++++++++++++++++++++++++++++++++------------------- drivers/dma/mv_xor.h | 1 + 2 files changed, 47 insertions(+), 26 deletions(-) --- a/drivers/dma/mv_xor.c +++ b/drivers/dma/mv_xor.c @@ -386,7 +386,8 @@ static void __mv_xor_slot_cleanup(struct dma_cookie_t cookie = 0; int busy = mv_chan_is_busy(mv_chan); u32 current_desc = mv_chan_get_current_desc(mv_chan); - int seen_current = 0; + int current_cleaned = 0; + struct mv_xor_desc *hw_desc; dev_dbg(mv_chan->device->common.dev, "%s %d\n", __func__, __LINE__); dev_dbg(mv_chan->device->common.dev, "current_desc %x\n", current_desc); @@ -398,38 +399,57 @@ static void __mv_xor_slot_cleanup(struct list_for_each_entry_safe(iter, _iter, &mv_chan->chain, chain_node) { - prefetch(_iter); - prefetch(&_iter->async_tx); - /* do not advance past the current descriptor loaded into the - * hardware channel, subsequent descriptors are either in - * process or have not been submitted - */ - if (seen_current) - break; - - /* stop the search if we reach the current descriptor and the - * channel is busy - */ - if (iter->async_tx.phys == current_desc) { - seen_current = 1; - if (busy) + /* clean finished descriptors */ + hw_desc = iter->hw_desc; + if (hw_desc->status & XOR_DESC_SUCCESS) { + cookie = mv_xor_run_tx_complete_actions(iter, mv_chan, + cookie); + + /* done processing desc, clean slot */ + mv_xor_clean_slot(iter, mv_chan); + + /* break if we did cleaned the current */ + if (iter->async_tx.phys == current_desc) { + current_cleaned = 1; break; + } + } else { + if (iter->async_tx.phys == current_desc) { + current_cleaned = 0; + break; + } } - - cookie = mv_xor_run_tx_complete_actions(iter, mv_chan, cookie); - - if (mv_xor_clean_slot(iter, mv_chan)) - break; } if ((busy == 0) && !list_empty(&mv_chan->chain)) { - struct mv_xor_desc_slot *chain_head; - chain_head = list_entry(mv_chan->chain.next, - struct mv_xor_desc_slot, - chain_node); - - mv_xor_start_new_chain(mv_chan, chain_head); + if (current_cleaned) { + /* + * current descriptor cleaned and removed, run + * from list head + */ + iter = list_entry(mv_chan->chain.next, + struct mv_xor_desc_slot, + chain_node); + mv_xor_start_new_chain(mv_chan, iter); + } else { + if (!list_is_last(&iter->chain_node, &mv_chan->chain)) { + /* + * descriptors are still waiting after + * current, trigger them + */ + iter = list_entry(iter->chain_node.next, + struct mv_xor_desc_slot, + chain_node); + mv_xor_start_new_chain(mv_chan, iter); + } else { + /* + * some descriptors are still waiting + * to be cleaned + */ + tasklet_schedule(&mv_chan->irq_tasklet); + } + } } if (cookie > 0) --- a/drivers/dma/mv_xor.h +++ b/drivers/dma/mv_xor.h @@ -30,6 +30,7 @@ #define XOR_OPERATION_MODE_XOR 0 #define XOR_OPERATION_MODE_MEMCPY 2 #define XOR_OPERATION_MODE_MEMSET 4 +#define XOR_DESC_SUCCESS 0x40000000 #define XOR_CURR_DESC(chan) (chan->mmr_base + 0x210 + (chan->idx * 4)) #define XOR_NEXT_DESC(chan) (chan->mmr_base + 0x200 + (chan->idx * 4)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/