cifs: fix a pending undercount of srv_count

The following commit reverted the changes to ref count
the server struct while scheduling a reconnect work:
823342524868 Revert "cifs: reconnect work should have reference on server struct"

However, a following change also introduced scheduling
of reconnect work, and assumed ref counting. This change
fixes that as well.

Fixes umount problems like:

[73496.157838] CPU: 5 PID: 1321389 Comm: umount Tainted: G        W  OE      6.7.0-060700rc6-generic #202312172332
[73496.157841] Hardware name: LENOVO 20MAS08500/20MAS08500, BIOS N2CET67W (1.50 ) 12/15/2022`
[73496.157843] RIP: 0010:cifs_put_tcp_session+0x17d/0x190 [cifs]
[73496.157906] Code: 5d 31 c0 31 d2 31 f6 31 ff c3 cc cc cc cc e8 4a 6e 14 e6 e9 f6 fe ff ff be 03 00 00 00 48 89 d7 e8 78 26 b3 e5 e9 e4 fe ff ff <0f> 0b e9 b1 fe ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90
[73496.157908] RSP: 0018:ffffc90003bcbcb8 EFLAGS: 00010286
[73496.157911] RAX: 00000000ffffffff RBX: ffff8885830fa800 RCX: 0000000000000000
[73496.157913] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[73496.157915] RBP: ffffc90003bcbcc8 R08: 0000000000000000 R09: 0000000000000000
[73496.157917] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[73496.157918] R13: ffff8887d56ba800 R14: 00000000ffffffff R15: ffff8885830fa800
[73496.157920] FS:  00007f1ff0e33800(0000) GS:ffff88887ba80000(0000) knlGS:0000000000000000
[73496.157922] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[73496.157924] CR2: 0000115f002e2010 CR3: 00000003d1e24005 CR4: 00000000003706f0
[73496.157926] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[73496.157928] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[73496.157929] Call Trace:
[73496.157931]  <TASK>
[73496.157933]  ? show_regs+0x6d/0x80
[73496.157936]  ? __warn+0x89/0x160
[73496.157939]  ? cifs_put_tcp_session+0x17d/0x190 [cifs]
[73496.157976]  ? report_bug+0x17e/0x1b0
[73496.157980]  ? handle_bug+0x51/0xa0
[73496.157983]  ? exc_invalid_op+0x18/0x80
[73496.157985]  ? asm_exc_invalid_op+0x1b/0x20
[73496.157989]  ? cifs_put_tcp_session+0x17d/0x190 [cifs]
[73496.158023]  ? cifs_put_tcp_session+0x1e/0x190 [cifs]
[73496.158057]  __cifs_put_smb_ses+0x2b5/0x540 [cifs]
[73496.158090]  ? tconInfoFree+0xc2/0x120 [cifs]
[73496.158130]  cifs_put_tcon.part.0+0x108/0x2b0 [cifs]
[73496.158173]  cifs_put_tlink+0x49/0x90 [cifs]
[73496.158220]  cifs_umount+0x56/0xb0 [cifs]
[73496.158258]  cifs_kill_sb+0x52/0x60 [cifs]
[73496.158306]  deactivate_locked_super+0x32/0xc0
[73496.158309]  deactivate_super+0x46/0x60
[73496.158311]  cleanup_mnt+0xc3/0x170
[73496.158314]  __cleanup_mnt+0x12/0x20
[73496.158330]  task_work_run+0x5e/0xa0
[73496.158333]  exit_to_user_mode_loop+0x105/0x130
[73496.158336]  exit_to_user_mode_prepare+0xa5/0xb0
[73496.158338]  syscall_exit_to_user_mode+0x29/0x60
[73496.158341]  do_syscall_64+0x6c/0xf0
[73496.158344]  ? syscall_exit_to_user_mode+0x37/0x60
[73496.158346]  ? do_syscall_64+0x6c/0xf0
[73496.158349]  ? exit_to_user_mode_prepare+0x30/0xb0
[73496.158353]  ? syscall_exit_to_user_mode+0x37/0x60
[73496.158355]  ? do_syscall_64+0x6c/0xf0

Reported-by: Robert Morris <rtm@csail.mit.edu>
Fixes: 705fc522fe9d ("cifs: handle when server starts supporting multichannel")
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index d49796d572a1468942ca073606ac23ddd4e5f24f..27bf9d25b1ac207a1d4f5277703877ac3974a155 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -411,8 +411,7 @@ skip_sess_setup:
        }
 
        if (smb2_command != SMB2_INTERNAL_CMD)
-               if (mod_delayed_work(cifsiod_wq, &server->reconnect, 0))
-                       cifs_put_tcp_session(server, false);
+               mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
 
        atomic_inc(&tconInfoReconnectCount);
 out: