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Commit | Line | Data |
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72fc6108 GKH |
1 | From foo@baz Mon Apr 9 10:16:32 CEST 2018 |
2 | From: Mike Christie <mchristi@redhat.com> | |
3 | Date: Tue, 28 Nov 2017 12:40:33 -0600 | |
4 | Subject: tcmu: release blocks for partially setup cmds | |
5 | ||
6 | From: Mike Christie <mchristi@redhat.com> | |
7 | ||
8 | ||
9 | [ Upstream commit 810b8153c4243d2012a6ec002ddd3bbc9a9ae8c2 ] | |
10 | ||
11 | If we cannot setup a cmd because we run out of ring space | |
12 | or global pages release the blocks before sleeping. This | |
13 | prevents a deadlock where dev0 has waiting_blocks set and | |
14 | needs N blocks, but dev1 to devX have each allocated N / X blocks | |
15 | and also hit the global block limit so they went to sleep. | |
16 | ||
17 | find_free_blocks is not able to take the sleeping dev's | |
18 | blocks becaause their waiting_blocks is set and even | |
19 | if it was not the block returned by find_last_bit could equal | |
20 | dbi_max. The latter will probably never happen because | |
21 | DATA_BLOCK_BITS is so high but in the next patches | |
22 | DATA_BLOCK_BITS and TCMU_GLOBAL_MAX_BLOCKS will be settable so | |
23 | it might be lower and could happen. | |
24 | ||
25 | Signed-off-by: Mike Christie <mchristi@redhat.com> | |
26 | Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> | |
27 | Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> | |
28 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
29 | --- | |
30 | drivers/target/target_core_user.c | 7 +++++++ | |
31 | 1 file changed, 7 insertions(+) | |
32 | ||
33 | --- a/drivers/target/target_core_user.c | |
34 | +++ b/drivers/target/target_core_user.c | |
35 | @@ -805,6 +805,13 @@ tcmu_queue_cmd_ring(struct tcmu_cmd *tcm | |
36 | int ret; | |
37 | DEFINE_WAIT(__wait); | |
38 | ||
39 | + /* | |
40 | + * Don't leave commands partially setup because the unmap | |
41 | + * thread might need the blocks to make forward progress. | |
42 | + */ | |
43 | + tcmu_cmd_free_data(tcmu_cmd, tcmu_cmd->dbi_cur); | |
44 | + tcmu_cmd_reset_dbi_cur(tcmu_cmd); | |
45 | + | |
46 | prepare_to_wait(&udev->wait_cmdr, &__wait, TASK_INTERRUPTIBLE); | |
47 | ||
48 | pr_debug("sleeping for ring space\n"); |