From cf6d1f0964fa9db57fc660caf51939d7a03359a1 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Wed, 21 Aug 2013 19:34:43 -0700 Subject: [PATCH] target: Release COMPARE_AND_WRITE mutex in generic failure path This patch adds a extra check for SCF_COMPARE_AND_WRITE within transport_generic_request_failure() to invoke the callback for compare_and_write_callback() or compare_and_write_done(), in order to release se_dev->caw_mutex from the generic failure path. It also adds to checks within compare_and_write_callback() to avoid processing when transport_generic_request_failure() occurs early enough that cmd->t_data_sg or cmd->t_bidi_data_sg have not been setup yet, nor se_dev->caw_mutex obtained from within sbc_compare_and_write(). v4 changes: - Add explicit check for cmd->transport_complete_callback in transport_generic_request_failure() to handle case where sbc_compare_and_write()clears callback pointer (Dan Carpenter) Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Martin Petersen Cc: Chris Mason Cc: James Bottomley Cc: Nicholas Bellinger Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_sbc.c | 7 +++++++ drivers/target/target_core_transport.c | 7 +++++++ 2 files changed, 14 insertions(+) diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index 5c822fd..2cd9acd 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -372,6 +372,13 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd) sense_reason_t ret = TCM_NO_SENSE; int rc, i; + /* + * Handle early failure in transport_generic_request_failure(), + * which will not have taken ->caw_mutex yet.. + */ + if (!cmd->t_data_sg || !cmd->t_bidi_data_sg) + return TCM_NO_SENSE; + buf = kzalloc(cmd->data_length, GFP_KERNEL); if (!buf) { pr_err("Unable to allocate compare_and_write buf\n"); diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index e53c59b..bcbc3d3 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -1559,6 +1559,13 @@ void transport_generic_request_failure(struct se_cmd *cmd, * For SAM Task Attribute emulation for failed struct se_cmd */ transport_complete_task_attr(cmd); + /* + * Handle special case for COMPARE_AND_WRITE failure, where the + * callback is expected to drop the per device ->caw_mutex. + */ + if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) && + cmd->transport_complete_callback) + cmd->transport_complete_callback(cmd); switch (sense_reason) { case TCM_NON_EXISTENT_LUN: -- 2.7.4