Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932244AbcDJUsd (ORCPT ); Sun, 10 Apr 2016 16:48:33 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:51695 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756596AbcDJSiB (ORCPT ); Sun, 10 Apr 2016 14:38:01 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Finn Thain , "Martin K. Petersen" Subject: [PATCH 4.5 039/238] ncr5380: Dont release lock for PIO transfer Date: Sun, 10 Apr 2016 11:33:36 -0700 Message-Id: <20160410183458.535746916@linuxfoundation.org> X-Mailer: git-send-email 2.8.0 In-Reply-To: <20160410183456.398741366@linuxfoundation.org> References: <20160410183456.398741366@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4304 Lines: 117 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Finn Thain commit 1678847ec93040ae8280d19c42ae0ba8a4233e6d upstream. The calls to NCR5380_transfer_pio() for DATA IN and DATA OUT phases will modify cmd->SCp.this_residual, cmd->SCp.ptr and cmd->SCp.buffer. That works as long as EH does not intervene, which became possible in atari_NCR5380.c when I changed the locking to bring it closer to NCR5380.c. If error recovery aborts the command, the scsi_cmnd in question and its buffer will be returned to the mid-layer. So the transfer has to cease, but it can't be stopped by the initiator because the target controls the bus phase. The problem does not arise if the lock is not released. That was fine for atari_scsi, because it implements DMA. For the other drivers, we have to release the lock and re-enable interrupts for long PIO data transfers. The solution is to split the transfer into small chunks. In between chunks the main loop releases the lock and re-enables interrupts. Thus interrupts can be serviced and eh_bus_reset_handler can intervene if need be. This fixes an oops in NCR5380_transfer_pio() that can happen when the EH abort handler is invoked during DATA IN or DATA OUT phase. Fixes: 11d2f63b9cf5 ("ncr5380: Change instance->host_lock to hostdata->lock") Reported-and-tested-by: Michael Schmitz Signed-off-by: Finn Thain Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/NCR5380.c | 16 +++++++++------- drivers/scsi/atari_NCR5380.c | 16 +++++++++------- 2 files changed, 18 insertions(+), 14 deletions(-) --- a/drivers/scsi/NCR5380.c +++ b/drivers/scsi/NCR5380.c @@ -1759,9 +1759,7 @@ static void NCR5380_information_transfer unsigned char msgout = NOP; int sink = 0; int len; -#if defined(PSEUDO_DMA) || defined(REAL_DMA_POLL) int transfersize; -#endif unsigned char *data; unsigned char phase, tmp, extended_msg[10], old_phase = 0xff; struct scsi_cmnd *cmd; @@ -1854,13 +1852,17 @@ static void NCR5380_information_transfer } else #endif /* defined(PSEUDO_DMA) || defined(REAL_DMA_POLL) */ { - spin_unlock_irq(&hostdata->lock); - NCR5380_transfer_pio(instance, &phase, - (int *)&cmd->SCp.this_residual, + /* Break up transfer into 3 ms chunks, + * presuming 6 accesses per handshake. + */ + transfersize = min((unsigned long)cmd->SCp.this_residual, + hostdata->accesses_per_ms / 2); + len = transfersize; + NCR5380_transfer_pio(instance, &phase, &len, (unsigned char **)&cmd->SCp.ptr); - spin_lock_irq(&hostdata->lock); + cmd->SCp.this_residual -= transfersize - len; } - break; + return; case PHASE_MSGIN: len = 1; data = &tmp; --- a/drivers/scsi/atari_NCR5380.c +++ b/drivers/scsi/atari_NCR5380.c @@ -1838,9 +1838,7 @@ static void NCR5380_information_transfer unsigned char msgout = NOP; int sink = 0; int len; -#if defined(REAL_DMA) int transfersize; -#endif unsigned char *data; unsigned char phase, tmp, extended_msg[10], old_phase = 0xff; struct scsi_cmnd *cmd; @@ -1983,18 +1981,22 @@ static void NCR5380_information_transfer } else #endif /* defined(REAL_DMA) */ { - spin_unlock_irq(&hostdata->lock); - NCR5380_transfer_pio(instance, &phase, - (int *)&cmd->SCp.this_residual, + /* Break up transfer into 3 ms chunks, + * presuming 6 accesses per handshake. + */ + transfersize = min((unsigned long)cmd->SCp.this_residual, + hostdata->accesses_per_ms / 2); + len = transfersize; + NCR5380_transfer_pio(instance, &phase, &len, (unsigned char **)&cmd->SCp.ptr); - spin_lock_irq(&hostdata->lock); + cmd->SCp.this_residual -= transfersize - len; } #if defined(CONFIG_SUN3) && defined(REAL_DMA) /* if we had intended to dma that command clear it */ if (sun3_dma_setup_done == cmd) sun3_dma_setup_done = NULL; #endif - break; + return; case PHASE_MSGIN: len = 1; data = &tmp;