• Andrew Morton's avatar
    x86: fix RTC lockdep warning: potential hardirq recursion · 795d45b2
    Andrew Morton authored
    After disabling both CONFIG_DEBUG_LOCKING_API_SELFTESTS and netconsole
    (using current mainline) I get a login prompt, and also...
    
    [    5.181668] SELinux: policy loaded with handle_unknown=deny
    [    5.183315] type=1403 audit(1202100038.157:3): policy loaded auid=4294967295 ses=4294967295
    [    5.822073] SELinux: initialized (dev usbfs, type usbfs), uses genfs_contexts
    [    7.819146] ------------[ cut here ]------------
    [    7.819146] WARNING: at kernel/lockdep.c:2033 trace_hardirqs_on+0x9b/0x10d()
    [    7.819146] Modules linked in: generic ext3 jbd ide_disk ide_core
    [    7.819146] Pid: 399, comm: hwclock Not tainted 2.6.24 #4
    [    7.819146]  [<c011d140>] warn_on_slowpath+0x41/0x51
    [    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
    [    7.819146]  [<c013770c>] ? check_usage_forwards+0x19/0x3b
    [    7.819146]  [<c01390c4>] ? __lock_acquire+0xac3/0xb0b
    [    7.819146]  [<c0108c98>] ? native_sched_clock+0x8b/0x9f
    [    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
    [    7.819146]  [<c030ca6c>] ? _spin_unlock_irq+0x22/0x42
    [    7.819146]  [<c013848b>] trace_hardirqs_on+0x9b/0x10d
    [    7.819146]  [<c030ca6c>] _spin_unlock_irq+0x22/0x42
    [    7.819146]  [<c011481e>] hpet_rtc_interrupt+0xdf/0x290
    [    7.819146]  [<c014ea90>] handle_IRQ_event+0x1a/0x46
    [    7.819146]  [<c014f8ea>] handle_edge_irq+0xbe/0xff
    [    7.819146]  [<c0106e08>] do_IRQ+0x6d/0x84
    [    7.819146]  [<c0105596>] common_interrupt+0x2e/0x34
    [    7.819146]  [<c013007b>] ? ktime_get_ts+0x8/0x3f
    [    7.819146]  [<c0139420>] ? lock_release+0x167/0x16f
    [    7.819146]  [<c017974a>] ? core_sys_select+0x2c/0x327
    [    7.819146]  [<c0179792>] core_sys_select+0x74/0x327
    [    7.819146]  [<c0108c98>] ? native_sched_clock+0x8b/0x9f
    [    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
    [    7.819146]  [<c030ca6c>] ? _spin_unlock_irq+0x22/0x42
    [    7.819146]  [<c01384d6>] ? trace_hardirqs_on+0xe6/0x10d
    [    7.819146]  [<c030ca77>] ? _spin_unlock_irq+0x2d/0x42
    [    7.819146]  [<c023b437>] ? rtc_do_ioctl+0x11b/0x677
    [    7.819146]  [<c01c487e>] ? inode_has_perm+0x5e/0x68
    [    7.819146]  [<c01364a9>] ? lock_release_holdtime+0x50/0x56
    [    7.819146]  [<c0108c98>] ? native_sched_clock+0x8b/0x9f
    [    7.819146]  [<c01c490b>] ? file_has_perm+0x83/0x8c
    [    7.819146]  [<c023ba08>] ? rtc_ioctl+0xf/0x11
    [    7.819146]  [<c017898d>] ? do_ioctl+0x55/0x67
    [    7.819146]  [<c0179d15>] sys_select+0x93/0x163
    [    7.819146]  [<c0104b39>] ? sysenter_past_esp+0x9a/0xa5
    [    7.819146]  [<c0104afe>] sysenter_past_esp+0x5f/0xa5
    [    7.819146]  =======================
    [    7.819146] ---[ end trace 96540ca301ffb84c ]---
    [    7.819210] rtc: lost 6 interrupts
    [    7.870668] type=1400 audit(1202128840.794:4): avc:  denied  { audit_write } for  pid=399 comm="hwclock" capability=29 scontext=system_u:system_r:hwclock_t:s0 tcontext=system_u:system_r:hwclock_t:s0 tclass=capability
    [    9.538866] input: PC Speaker as /class/input/input5
    
    Because hpet_rtc_interrupt()'s call to get_rtc_time() ends up
    resolving to include/asm-generic/rtc.h's (hilariously inlined)
    get_rtc_time(), which does spin_unlock_irq() from hard IRQ context.
    
    The obvious patch fixes it.
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    795d45b2
rtc.h 5.24 KB