#7479 BLOC Never A: Suspend failing due to EC warning

[Zarro Boogs per Child]

#7479: Suspend failing due to EC warning
------------------------+---------------------------------------------------
   Reporter:  cjb       |       Owner:  dsaxena       
       Type:  defect    |      Status:  new           
   Priority:  blocker   |   Milestone:  Never Assigned
  Component:  kernel    |     Version:  Update.1      
 Resolution:            |    Keywords:                
Next_action:  diagnose  |    Verified:  0             
  Blockedby:            |    Blocking:                
------------------------+---------------------------------------------------

Comment(by dsaxena):

 Replying to [comment:2 cjb]:
 > What I can't explain is the EBUSY.  It does look like it could be that
 mutex line, given the top three functions in the stack trace:
 >
 > {{{
 > [ 7718.350390]  [<c041492b>] warn_on_slowpath+0x40/0x4f
 > [ 7718.350390]  [<c05e5db2>] __down_trylock+0x3a/0x43
 > [ 7718.350390]  [<c05eb7e7>] __down_failed_trylock+0x7/0xc
 > }}}

 This stack trace is a bit odd in general:

 {{{

 [ 7697.409260] Pid: 1528, comm: bash Not tainted
 2.6.25-20080710.3.olpc.14813f826d6ccaf #1
 [ 7697.409260]  [<c041492b>] warn_on_slowpath+0x40/0x4f           #
 Warning message printed here
 [ 7697.409260]  [<c05e5db2>] __down_trylock+0x3a/0x43
 [ 7697.409260]  [<c05eb7e7>] __down_failed_trylock+0x7/0xc
 [ 7697.409260]  [<c05ebc47>] _spin_unlock+0xf/0x22                #
 [ 7697.409260]  [<c04154b0>] vprintk+0x27d/0x2f7                  # Other
 things happening here
 [ 7697.409260]  [<c04da506>] delay_tsc+0x2c/0x43                  # What
 exactly?
 [ 7697.409260]  [<c04da506>] delay_tsc+0x2c/0x43
 [ 7697.409260]  [<c041553e>] printk+0x14/0x18
 [ 7697.409260]  [<c05ebcb2>] _spin_unlock_irqrestore+0x14/0x29
 [ 7697.409260]  [<c0409c05>] olpc_ec_cmd+0x17d/0x188               #
 WARN_ON() call is here
 [ 7697.409260]  [<c040a178>] olpc_ec_mask_set+0x43/0x7a
 [ 7697.409260]  [<c040a36d>] olpc_pm_enter+0x36/0x49
 [ 7697.409260]  [<c0430b99>] suspend_devices_and_enter+0xd8/0x118
 [ 7697.409260]  [<c0430d01>] enter_state+0x10a/0x179
 [ 7697.409260]  [<c0430e00>] state_store+0x90/0xa8
 [ 7697.409260]  [<c0430d70>] state_store+0x0/0xa8
 [ 7697.409260]  [<c04d6623>] kobj_attr_store+0x18/0x1c
 [ 7697.409260]  [<c048b329>] sysfs_write_file+0x9f/0xd3
 [ 7697.409260]  [<c048b28a>] sysfs_write_file+0x0/0xd3
 [ 7697.409260]  [<c0456325>] vfs_write+0x83/0xfc
 [ 7697.409260]  [<c04567e1>] sys_write+0x3c/0x63
 [ 7697.409260]  [<c0403782>] sysenter_past_esp+0x5f/0x85
 }}}

 I'm going to commit a change to testing repo to enable CONFIG_DEBUG_MUTEX
 so we can get more information next time we see this in testing.

-- 
Ticket URL: <http://dev.laptop.org/ticket/7479#comment:3>
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