path: root/drivers/target/target_core_user.c
diff options
authorMike Christie <mchristi@redhat.com>2017-11-28 12:40:33 -0600
committerNicholas Bellinger <nab@linux-iscsi.org>2018-01-12 15:07:14 -0800
commit810b8153c4243d2012a6ec002ddd3bbc9a9ae8c2 (patch)
treef0c5a0269bac1daf24567b64f3ca542675f2761c /drivers/target/target_core_user.c
parent6fddcb775477bb2213bd76ab62145645eb570f33 (diff)
tcmu: release blocks for partially setup cmds
If we cannot setup a cmd because we run out of ring space or global pages release the blocks before sleeping. This prevents a deadlock where dev0 has waiting_blocks set and needs N blocks, but dev1 to devX have each allocated N / X blocks and also hit the global block limit so they went to sleep. find_free_blocks is not able to take the sleeping dev's blocks becaause their waiting_blocks is set and even if it was not the block returned by find_last_bit could equal dbi_max. The latter will probably never happen because DATA_BLOCK_BITS is so high but in the next patches DATA_BLOCK_BITS and TCMU_GLOBAL_MAX_BLOCKS will be settable so it might be lower and could happen. Signed-off-by: Mike Christie <mchristi@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target/target_core_user.c')
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 43583a792439..c7541f090453 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -807,6 +807,13 @@ tcmu_queue_cmd_ring(struct tcmu_cmd *tcmu_cmd)
int ret;
+ /*
+ * Don't leave commands partially setup because the unmap
+ * thread might need the blocks to make forward progress.
+ */
+ tcmu_cmd_free_data(tcmu_cmd, tcmu_cmd->dbi_cur);
+ tcmu_cmd_reset_dbi_cur(tcmu_cmd);
prepare_to_wait(&udev->wait_cmdr, &__wait, TASK_INTERRUPTIBLE);
pr_debug("sleeping for ring space\n");

Privacy Policy