Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Support for Philips TDA1545 and/or configurable I2S data output #20

Open
eflukx opened this issue Sep 20, 2013 · 0 comments
Open

Support for Philips TDA1545 and/or configurable I2S data output #20

eflukx opened this issue Sep 20, 2013 · 0 comments

Comments

@eflukx
Copy link

eflukx commented Sep 20, 2013

I hooked up a TDA1545 (yes thats not a typo) DAC IC and tried to run it with the TDA1541 driver. Mplayer seems to play correctly, but there's loads of white noise with the music playing faintly in the back.

This looks to me as some sort of I2S formatting problem. I have had proper sound before using the same hw setup and using Phil Poole's (userspace and kernel) software in which I tweaked the TXC_A and MODE_A registers myself.

As your code is a bit more complex so I don't know what I will break if I go fiddlin' around with the parameters myself. Maybe you could have a look at the TDA1545 datasheet and include a driver for it (should be TDA5141 driver with 1 or 2 tweaks).

As the I2S interface on the BCM2708 is very flexible would it be an idea to have a "generic" I2S driver in which the formatting settings can be done as kernel module options?

Datasheet to the TDA1545: http://pdf.datasheetcatalog.com/datasheet/philips/TDA1545A_T_3.pdf

koalo pushed a commit that referenced this issue Nov 19, 2013
Currently IOP3XX_PERIPHERAL_VIRT_BASE conflicts with PCI_IO_VIRT_BASE:

					address         size
	PCI_IO_VIRT_BASE                0xfee00000      0x200000
	IOP3XX_PERIPHERAL_VIRT_BASE     0xfeffe000      0x2000

Fix by moving IOP3XX_PERIPHERAL_VIRT_BASE below PCI_IO_VIRT_BASE.

The patch fixes the following kernel panic with 3.9-rc1 on iop3xx boards:

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Linux version 3.9.0-rc1-iop32x (aaro@blackmetal) (gcc version 4.7.2 (GCC) ) #20 PREEMPT Tue Mar 5 16:44:36 EET 2013
[    0.000000] bootconsole [earlycon0] enabled
[    0.000000] ------------[ cut here ]------------
[    0.000000] kernel BUG at mm/vmalloc.c:1145!
[    0.000000] Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
[    0.000000] Modules linked in:
[    0.000000] CPU: 0    Not tainted  (3.9.0-rc1-iop32x #20)
[    0.000000] PC is at vm_area_add_early+0x4c/0x88
[    0.000000] LR is at add_static_vm_early+0x14/0x68
[    0.000000] pc : [<c03e74a8>]    lr : [<c03e1c40>]    psr: 800000d3
[    0.000000] sp : c03ffee4  ip : dfffdf88  fp : c03ffef4
[    0.000000] r10: 00000002  r9 : 000000cf  r8 : 00000653
[    0.000000] r7 : c040eca8  r6 : c03e2408  r5 : dfffdf60  r4 : 00200000
[    0.000000] r3 : dfffdfd8  r2 : feffe000  r1 : ff000000  r0 : dfffdf60
[    0.000000] Flags: Nzcv  IRQs off  FIQs off  Mode SVC_32  ISA ARM  Segment kernel
[    0.000000] Control: 0000397f  Table: a0004000  DAC: 00000017
[    0.000000] Process swapper (pid: 0, stack limit = 0xc03fe1b8)
[    0.000000] Stack: (0xc03ffee4 to 0xc0400000)
[    0.000000] fee0:          00200000 c03fff0c c03ffef8 c03e1c40 c03e7468 00200000 fee00000
[    0.000000] ff00: c03fff2c c03fff10 c03e23e4 c03e1c38 feffe000 c0408ee4 ff000000 c0408f04
[    0.000000] ff20: c03fff3c c03fff30 c03e2434 c03e23b4 c03fff84 c03fff40 c03e2c94 c03e2414
[    0.000000] ff40: c03f8878 c03f6410 ffff0000 000bffff 00001000 00000008 c03fff84 c03f6410
[    0.000000] ff60: c04227e8 c03fffd4 a0008000 c03f8878 69052e30 c02f96eb c03fffbc c03fff88
[    0.000000] ff80: c03e044c c03e268c 00000000 0000397f c0385130 00000001 ffffffff c03f8874
[    0.000000] ffa0: dfffffff a0004000 69052e30 a03f61a0 c03ffff4 c03fffc0 c03dd5cc c03e0184
[    0.000000] ffc0: 00000000 00000000 00000000 00000000 00000000 c03f8878 0000397d c040601c
[    0.000000] ffe0: c03f8874 c0408674 00000000 c03ffff8 a0008040 c03dd558 00000000 00000000
[    0.000000] Backtrace:
[    0.000000] [<c03e745c>] (vm_area_add_early+0x0/0x88) from [<c03e1c40>] (add_static_vm_early+0x14/0x68)

Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
koalo pushed a commit that referenced this issue Nov 19, 2013
…s struct file

commit e4daf1f upstream.

The following call chain:
------------------------------------------------------------
nfs4_get_vfs_file
- nfsd_open
  - dentry_open
    - do_dentry_open
      - __get_file_write_access
        - get_write_access
          - return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
------------------------------------------------------------

can result in the following state:
------------------------------------------------------------
struct nfs4_file {
...
  fi_fds = {0xffff880c1fa65c80, 0xffffffffffffffe6, 0x0},
  fi_access = {{
      counter = 0x1
    }, {
      counter = 0x0
    }},
...
------------------------------------------------------------

1) First time around, in nfs4_get_vfs_file() fp->fi_fds[O_WRONLY] is
NULL, hence nfsd_open() is called where we get status set to an error
and fp->fi_fds[O_WRONLY] to -ETXTBSY. Thus we do not reach
nfs4_file_get_access() and fi_access[O_WRONLY] is not incremented.

2) Second time around, in nfs4_get_vfs_file() fp->fi_fds[O_WRONLY] is
NOT NULL (-ETXTBSY), so nfsd_open() is NOT called, but
nfs4_file_get_access() IS called and fi_access[O_WRONLY] is incremented.
Thus we leave a landmine in the form of the nfs4_file data structure in
an incorrect state.

3) Eventually, when __nfs4_file_put_access() is called it finds
fi_access[O_WRONLY] being non-zero, it decrements it and calls
nfs4_file_put_fd() which tries to fput -ETXTBSY.
------------------------------------------------------------
...
     [exception RIP: fput+0x9]
     RIP: ffffffff81177fa9  RSP: ffff88062e365c90  RFLAGS: 00010282
     RAX: ffff880c2b3d99cc  RBX: ffff880c2b3d9978  RCX: 0000000000000002
     RDX: dead000000100101  RSI: 0000000000000001  RDI: ffffffffffffffe6
     RBP: ffff88062e365c90   R8: ffff88041fe797d8   R9: ffff88062e365d58
     R10: 0000000000000008  R11: 0000000000000000  R12: 0000000000000001
     R13: 0000000000000007  R14: 0000000000000000  R15: 0000000000000000
     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
  #9 [ffff88062e365c98] __nfs4_file_put_access at ffffffffa0562334 [nfsd]
 #10 [ffff88062e365cc8] nfs4_file_put_access at ffffffffa05623ab [nfsd]
 #11 [ffff88062e365ce8] free_generic_stateid at ffffffffa056634d [nfsd]
 #12 [ffff88062e365d18] release_open_stateid at ffffffffa0566e4b [nfsd]
 #13 [ffff88062e365d38] nfsd4_close at ffffffffa0567401 [nfsd]
 #14 [ffff88062e365d88] nfsd4_proc_compound at ffffffffa0557f28 [nfsd]
 #15 [ffff88062e365dd8] nfsd_dispatch at ffffffffa054543e [nfsd]
 #16 [ffff88062e365e18] svc_process_common at ffffffffa04ba5a4 [sunrpc]
 #17 [ffff88062e365e98] svc_process at ffffffffa04babe0 [sunrpc]
 #18 [ffff88062e365eb8] nfsd at ffffffffa0545b62 [nfsd]
 #19 [ffff88062e365ee8] kthread at ffffffff81090886
 #20 [ffff88062e365f48] kernel_thread at ffffffff8100c14a
------------------------------------------------------------

Signed-off-by: Harshula Jayasuriya <harshula@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
koalo pushed a commit that referenced this issue Aug 4, 2014
…rupt handler

Mutexes should not be acquired in interrupt context. While the trylock
fastpath is arguably safe on all implementations, the slowpath
unlock path definitely isn't. This fixes the following lockdep splat:

[   13.044313] ------------[ cut here ]------------
[   13.044367] WARNING: at /c/kernel-tests/src/tip/kernel/mutex.c:858 mutex_trylock+0x87/0x220()
[   13.044378] DEBUG_LOCKS_WARN_ON(in_interrupt())
[   13.044378] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.10.0-rc4-00296-ga2963dd #20
[   13.044379] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
[   13.044390]  0000000000000009 ffff88000de039f8 ffffffff81fc86d5 ffff88000de03a38
[   13.044395]  ffffffff810d511b ffff880000000018 ffff88000f33c690 0000000000000001
[   13.044398]  00000000000003f0 ffff88000f4677c8 0000000000000000 ffff88000de03a98
[   13.044400] Call Trace:
[   13.044412]  <IRQ>  [<ffffffff81fc86d5>] dump_stack+0x19/0x1b
[   13.044441]  [<ffffffff810d511b>] warn_slowpath_common+0x6b/0x90
[   13.044445]  [<ffffffff810d51a6>] warn_slowpath_fmt+0x46/0x50
[   13.044448]  [<ffffffff81fd34d7>] mutex_trylock+0x87/0x220
[   13.044482]  [<ffffffff8186484d>] cirrus_dirty_update+0x1cd/0x330
[   13.044486]  [<ffffffff818649e8>] cirrus_imageblit+0x38/0x50
[   13.044506]  [<ffffffff8165782e>] soft_cursor+0x22e/0x240
[   13.044510]  [<ffffffff81656c31>] bit_cursor+0x581/0x5b0
[   13.044525]  [<ffffffff815de9f4>] ? vsnprintf+0x124/0x670
[   13.044529]  [<ffffffff81651333>] ? get_color.isra.16+0x43/0x130
[   13.044532]  [<ffffffff81653fca>] fbcon_cursor+0x18a/0x1d0
[   13.044535]  [<ffffffff816566b0>] ? update_attr.isra.2+0xa0/0xa0
[   13.044556]  [<ffffffff81754b82>] hide_cursor+0x32/0xa0
[   13.044565]  [<ffffffff81755bd3>] vt_console_print+0x103/0x3b0
[   13.044569]  [<ffffffff810d58ac>] ? print_time+0x9c/0xb0
[   13.044576]  [<ffffffff810d5960>] ? print_prefix+0xa0/0xc0
[   13.044580]  [<ffffffff810d63f6>] call_console_drivers.constprop.6+0x146/0x1f0
[   13.044593]  [<ffffffff815f9b38>] ? do_raw_spin_unlock+0xc8/0x100
[   13.044597]  [<ffffffff810d6f27>] console_unlock+0x2f7/0x460
[   13.044600]  [<ffffffff810d787a>] vprintk_emit+0x59a/0x5e0
[   13.044615]  [<ffffffff81fb676c>] printk+0x4d/0x4f
[   13.044650]  [<ffffffff82ba5511>] print_local_APIC+0x28/0x41c
[   13.044672]  [<ffffffff8114db55>] generic_smp_call_function_single_interrupt+0x145/0x2b0
[   13.044688]  [<ffffffff8106f9e7>] smp_call_function_single_interrupt+0x27/0x40
[   13.044697]  [<ffffffff81fd8f72>] call_function_single_interrupt+0x72/0x80
[   13.044707]  <EOI>  [<ffffffff81078166>] ? native_safe_halt+0x6/0x10
[   13.044717]  [<ffffffff811425cd>] ? trace_hardirqs_on+0xd/0x10
[   13.044738]  [<ffffffff8104f669>] default_idle+0x59/0x120
[   13.044742]  [<ffffffff810501e8>] arch_cpu_idle+0x18/0x40
[   13.044754]  [<ffffffff811320c5>] cpu_startup_entry+0x235/0x410
[   13.044763]  [<ffffffff81f9e781>] rest_init+0xd1/0xe0
[   13.044766]  [<ffffffff81f9e6b5>] ? rest_init+0x5/0xe0
[   13.044778]  [<ffffffff82b93ec2>] start_kernel+0x425/0x493
[   13.044781]  [<ffffffff82b93810>] ? repair_env_string+0x5e/0x5e
[   13.044786]  [<ffffffff82b93595>] x86_64_start_reservations+0x2a/0x2c
[   13.044789]  [<ffffffff82b93688>] x86_64_start_kernel+0xf1/0x100
[   13.044799] ---[ end trace 113ad28772af4058 ]---

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
koalo pushed a commit that referenced this issue Aug 4, 2014
Several people reported the warning: "kernel BUG at kernel/timer.c:729!"
and the stack trace is:

	#7 [ffff880214d25c10] mod_timer+501 at ffffffff8106d905
	#8 [ffff880214d25c50] br_multicast_del_pg.isra.20+261 at ffffffffa0731d25 [bridge]
	#9 [ffff880214d25c80] br_multicast_disable_port+88 at ffffffffa0732948 [bridge]
	#10 [ffff880214d25cb0] br_stp_disable_port+154 at ffffffffa072bcca [bridge]
	#11 [ffff880214d25ce8] br_device_event+520 at ffffffffa072a4e8 [bridge]
	#12 [ffff880214d25d18] notifier_call_chain+76 at ffffffff8164aafc
	#13 [ffff880214d25d50] raw_notifier_call_chain+22 at ffffffff810858f6
	#14 [ffff880214d25d60] call_netdevice_notifiers+45 at ffffffff81536aad
	#15 [ffff880214d25d80] dev_close_many+183 at ffffffff81536d17
	#16 [ffff880214d25dc0] rollback_registered_many+168 at ffffffff81537f68
	#17 [ffff880214d25de8] rollback_registered+49 at ffffffff81538101
	#18 [ffff880214d25e10] unregister_netdevice_queue+72 at ffffffff815390d8
	#19 [ffff880214d25e30] __tun_detach+272 at ffffffffa074c2f0 [tun]
	#20 [ffff880214d25e88] tun_chr_close+45 at ffffffffa074c4bd [tun]
	#21 [ffff880214d25ea8] __fput+225 at ffffffff8119b1f1
	#22 [ffff880214d25ef0] ____fput+14 at ffffffff8119b3fe
	#23 [ffff880214d25f00] task_work_run+159 at ffffffff8107cf7f
	#24 [ffff880214d25f30] do_notify_resume+97 at ffffffff810139e1
	#25 [ffff880214d25f50] int_signal+18 at ffffffff8164f292

this is due to I forgot to check if mp->timer is armed in
br_multicast_del_pg(). This bug is introduced by
commit 9f00b2e (bridge: only expire the mdb entry
when query is received).

Same for __br_mdb_del().

Tested-by: poma <pomidorabelisima@gmail.com>
Reported-by: LiYonghua <809674045@qq.com>
Reported-by: Robert Hancock <hancockrwd@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
koalo pushed a commit that referenced this issue Aug 4, 2014
…s struct file

The following call chain:
------------------------------------------------------------
nfs4_get_vfs_file
- nfsd_open
  - dentry_open
    - do_dentry_open
      - __get_file_write_access
        - get_write_access
          - return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
------------------------------------------------------------

can result in the following state:
------------------------------------------------------------
struct nfs4_file {
...
  fi_fds = {0xffff880c1fa65c80, 0xffffffffffffffe6, 0x0},
  fi_access = {{
      counter = 0x1
    }, {
      counter = 0x0
    }},
...
------------------------------------------------------------

1) First time around, in nfs4_get_vfs_file() fp->fi_fds[O_WRONLY] is
NULL, hence nfsd_open() is called where we get status set to an error
and fp->fi_fds[O_WRONLY] to -ETXTBSY. Thus we do not reach
nfs4_file_get_access() and fi_access[O_WRONLY] is not incremented.

2) Second time around, in nfs4_get_vfs_file() fp->fi_fds[O_WRONLY] is
NOT NULL (-ETXTBSY), so nfsd_open() is NOT called, but
nfs4_file_get_access() IS called and fi_access[O_WRONLY] is incremented.
Thus we leave a landmine in the form of the nfs4_file data structure in
an incorrect state.

3) Eventually, when __nfs4_file_put_access() is called it finds
fi_access[O_WRONLY] being non-zero, it decrements it and calls
nfs4_file_put_fd() which tries to fput -ETXTBSY.
------------------------------------------------------------
...
     [exception RIP: fput+0x9]
     RIP: ffffffff81177fa9  RSP: ffff88062e365c90  RFLAGS: 00010282
     RAX: ffff880c2b3d99cc  RBX: ffff880c2b3d9978  RCX: 0000000000000002
     RDX: dead000000100101  RSI: 0000000000000001  RDI: ffffffffffffffe6
     RBP: ffff88062e365c90   R8: ffff88041fe797d8   R9: ffff88062e365d58
     R10: 0000000000000008  R11: 0000000000000000  R12: 0000000000000001
     R13: 0000000000000007  R14: 0000000000000000  R15: 0000000000000000
     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
  #9 [ffff88062e365c98] __nfs4_file_put_access at ffffffffa0562334 [nfsd]
 #10 [ffff88062e365cc8] nfs4_file_put_access at ffffffffa05623ab [nfsd]
 #11 [ffff88062e365ce8] free_generic_stateid at ffffffffa056634d [nfsd]
 #12 [ffff88062e365d18] release_open_stateid at ffffffffa0566e4b [nfsd]
 #13 [ffff88062e365d38] nfsd4_close at ffffffffa0567401 [nfsd]
 #14 [ffff88062e365d88] nfsd4_proc_compound at ffffffffa0557f28 [nfsd]
 #15 [ffff88062e365dd8] nfsd_dispatch at ffffffffa054543e [nfsd]
 #16 [ffff88062e365e18] svc_process_common at ffffffffa04ba5a4 [sunrpc]
 #17 [ffff88062e365e98] svc_process at ffffffffa04babe0 [sunrpc]
 #18 [ffff88062e365eb8] nfsd at ffffffffa0545b62 [nfsd]
 #19 [ffff88062e365ee8] kthread at ffffffff81090886
 #20 [ffff88062e365f48] kernel_thread at ffffffff8100c14a
------------------------------------------------------------

Cc: stable@vger.kernel.org
Signed-off-by: Harshula Jayasuriya <harshula@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
koalo pushed a commit that referenced this issue Aug 4, 2014
When booting secondary CPUs, announce_cpu() is called to show which cpu has
been brought up. For example:

[    0.402751] smpboot: Booting Node   0, Processors  #1 #2 #3 #4 #5 OK
[    0.525667] smpboot: Booting Node   1, Processors  #6 #7 #8 #9 #10 #11 OK
[    0.755592] smpboot: Booting Node   0, Processors  #12 #13 #14 #15 #16 #17 OK
[    0.890495] smpboot: Booting Node   1, Processors  #18 #19 #20 #21 #22 #23

But the last "OK" is lost, because 'nr_cpu_ids-1' represents the maximum
possible cpu id. It should use the maximum present cpu id in case not all
CPUs booted up.

Signed-off-by: Libin <huawei.libin@huawei.com>
Cc: <guohanjun@huawei.com>
Cc: <wangyijing@huawei.com>
Cc: <fenghua.yu@intel.com>
Cc: <paul.gortmaker@windriver.com>
Link: http://lkml.kernel.org/r/1378378676-18276-1-git-send-email-huawei.libin@huawei.com
[ tweaked the changelog, removed unnecessary line break, tweaked the format to align the fields vertically. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
koalo pushed a commit that referenced this issue Aug 4, 2014
…ssion()

commit 3dc91d4 upstream.

While running stress tests on adding and deleting ftrace instances I hit
this bug:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
  IP: selinux_inode_permission+0x85/0x160
  PGD 63681067 PUD 7ddbe067 PMD 0
  Oops: 0000 [#1] PREEMPT
  CPU: 0 PID: 5634 Comm: ftrace-test-mki Not tainted 3.13.0-rc4-test-00033-gd2a6dde-dirty #20
  Hardware name:                  /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006
  task: ffff880078375800 ti: ffff88007ddb0000 task.ti: ffff88007ddb0000
  RIP: 0010:[<ffffffff812d8bc5>]  [<ffffffff812d8bc5>] selinux_inode_permission+0x85/0x160
  RSP: 0018:ffff88007ddb1c48  EFLAGS: 00010246
  RAX: 0000000000000000 RBX: 0000000000800000 RCX: ffff88006dd43840
  RDX: 0000000000000001 RSI: 0000000000000081 RDI: ffff88006ee46000
  RBP: ffff88007ddb1c88 R08: 0000000000000000 R09: ffff88007ddb1c54
  R10: 6e6576652f6f6f66 R11: 0000000000000003 R12: 0000000000000000
  R13: 0000000000000081 R14: ffff88006ee46000 R15: 0000000000000000
  FS:  00007f217b5b6700(0000) GS:ffffffff81e21000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033^M
  CR2: 0000000000000020 CR3: 000000006a0fe000 CR4: 00000000000007f0
  Call Trace:
    security_inode_permission+0x1c/0x30
    __inode_permission+0x41/0xa0
    inode_permission+0x18/0x50
    link_path_walk+0x66/0x920
    path_openat+0xa6/0x6c0
    do_filp_open+0x43/0xa0
    do_sys_open+0x146/0x240
    SyS_open+0x1e/0x20
    system_call_fastpath+0x16/0x1b
  Code: 84 a1 00 00 00 81 e3 00 20 00 00 89 d8 83 c8 02 40 f6 c6 04 0f 45 d8 40 f6 c6 08 74 71 80 cf 02 49 8b 46 38 4c 8d 4d cc 45 31 c0 <0f> b7 50 20 8b 70 1c 48 8b 41 70 89 d9 8b 78 04 e8 36 cf ff ff
  RIP  selinux_inode_permission+0x85/0x160
  CR2: 0000000000000020

Investigating, I found that the inode->i_security was NULL, and the
dereference of it caused the oops.

in selinux_inode_permission():

	isec = inode->i_security;

	rc = avc_has_perm_noaudit(sid, isec->sid, isec->sclass, perms, 0, &avd);

Note, the crash came from stressing the deletion and reading of debugfs
files.  I was not able to recreate this via normal files.  But I'm not
sure they are safe.  It may just be that the race window is much harder
to hit.

What seems to have happened (and what I have traced), is the file is
being opened at the same time the file or directory is being deleted.
As the dentry and inode locks are not held during the path walk, nor is
the inodes ref counts being incremented, there is nothing saving these
structures from being discarded except for an rcu_read_lock().

The rcu_read_lock() protects against freeing of the inode, but it does
not protect freeing of the inode_security_struct.  Now if the freeing of
the i_security happens with a call_rcu(), and the i_security field of
the inode is not changed (it gets freed as the inode gets freed) then
there will be no issue here.  (Linus Torvalds suggested not setting the
field to NULL such that we do not need to check if it is NULL in the
permission check).

Note, this is a hack, but it fixes the problem at hand.  A real fix is
to restructure the destroy_inode() to call all the destructor handlers
from the RCU callback.  But that is a major job to do, and requires a
lot of work.  For now, we just band-aid this bug with this fix (it
works), and work on a more maintainable solution in the future.

Link: http://lkml.kernel.org/r/20140109101932.0508dec7@gandalf.local.home
Link: http://lkml.kernel.org/r/20140109182756.17abaaa8@gandalf.local.home

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

No branches or pull requests

1 participant