Re: [PATCH] cifs: allow calling cifs_build_path_to_root on incomplete cifs_sb

[Robbert Kouprie <robbert-C1IQQP51G3M@public.gmane.org>]

Hi Jeff,

Op 6-12-2010 13:15, Jeff Layton schreef:
> It's possible that cifs_mount will call cifs_build_path_to_root on a
> newly instantiated cifs_sb. In that case, it's likely that the
> master_tlink pointer has not yet been instantiated.
> 
> Fix this by having cifs_build_path_to_root take a cifsTconInfo pointer
> as well, and have the caller pass that in.

I still get an oops on 2.6.37-rc4-git5 with the patch applied:

 BUG: unable to handle kernel NULL pointer dereference at 0000001c
 IP: [<f8fd533b>] cifs_sb_master_tcon+0x3/0x7 [cifs]
 *pde = 00000000
 Oops: 0000 [#1] SMP
 last sysfs file: /sys/devices/virtual/bdi/cifs-2/uevent
 Modules linked in: hmac nls_utf8 cifs nls_base xfs exportfs loop
snd_pcm parport_pc parport tpm_tis tpm tpm_bios snd_timer snd soundcore
snd_page_alloc psmouse evdev pcspkr serio_raw i2c_piix4 i2c_core shpchp
container pci_hotplug processor thermal_sys ac button ext3 jbd mbcache
sd_mod crc_t10dif ide_cd_mod cdrom ata_generic ata_piix libata floppy
e1000 mptspi mptscsih mptbase scsi_transport_spi scsi_mod piix ide_core
[last unloaded: scsi_wait_scan]

 Pid: 1362, comm: ls Not tainted 2.6.37-rc4-git5 #2 440BX Desktop
Reference Platform/VMware Virtual Platform
 EIP: 0060:[<f8fd533b>] EFLAGS: 00010286 CPU: 0
 EIP is at cifs_sb_master_tcon+0x3/0x7 [cifs]
 EAX: 00000000 EBX: f7156800 ECX: 40000040 EDX: 00000002
 ESI: f7156800 EDI: f7156a00 EBP: 00000000 ESP: f72fddb0
  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
 Process ls (pid: 1362, ti=f72fc000 task=f71379e0 task.ti=f72fc000)
 Stack:
  f8fe14f3 002c80d0 00000000 f7156a00 f7156800 00000000 00000000 f8fcc96b
  0000007f f7156838 f5073d80 f50ac840 f8ff9f30 f8fcc7fd f522b000 c10b8301
  f50ac900 f5073d80 00000000 f50ac900 f50ac900 f72fded4 00000000 f8febc6f
 Call Trace:
  [<f8fe14f3>] ? cifs_root_iget+0x1e/0x13f [cifs]
  [<f8fcc96b>] ? cifs_do_mount+0x16e/0x247 [cifs]
  [<f8fcc7fd>] ? cifs_do_mount+0x0/0x247 [cifs]
  [<c10b8301>] ? vfs_kern_mount+0x9f/0x185
  [<f8febc6f>] ? cifs_dfs_follow_mountpoint+0x233/0x3cc [cifs]
  [<c10bec73>] ? do_follow_link+0xb6/0x1b1
  [<c10bf000>] ? link_path_walk+0x292/0x372
  [<c10bf1a2>] ? path_walk+0x4f/0xae
  [<c10bf2d3>] ? do_path_lookup+0x1f/0x69
  [<c10bfb70>] ? user_path_at+0x37/0x5f
  [<c1098af9>] ? vma_prio_tree_insert+0x17/0x2d
  [<c10b9981>] ? vfs_fstatat+0x2a/0x50
  [<c10b99e8>] ? vfs_lstat+0x13/0x15
  [<c10b99f9>] ? sys_lstat64+0xf/0x23
  [<c1052a04>] ? sys_futex+0xfe/0x112
  [<c10b500c>] ? filp_close+0x4e/0x54
  [<c127f54f>] ? do_page_fault+0x0/0x36b
  [<c1002f9f>] ? sysenter_do_call+0x12/0x28
 Code: c8 59 5f 39 ee 0f 8c 49 ff ff ff 8b 44 24 60 65 33 05 14 00 00 00
74 05 e8 ef 9b 05 c8 83 c4 64 5b 5e 5f 5d c3 90 90 90 8b 40 08 <8b> 40
1c c3 55 89 c5 83 3d a4 47 3b c1 00 57 89 d7 56 89 ce 53
 EIP: [<f8fd533b>] cifs_sb_master_tcon+0x3/0x7 [cifs] SS:ESP 0068:f72fddb0
 CR2: 000000000000001c
 ---[ end trace 61b6103d05293c43 ]---

Regards,
Robbert