• Kees Cook's avatar
    pstore: Convert buf_lock to semaphore · ea84b580
    Kees Cook authored
    Instead of running with interrupts disabled, use a semaphore. This should
    make it easier for backends that may need to sleep (e.g. EFI) when
    performing a write:
    
    |BUG: sleeping function called from invalid context at kernel/sched/completion.c:99
    |in_atomic(): 1, irqs_disabled(): 1, pid: 2236, name: sig-xstate-bum
    |Preemption disabled at:
    |[<ffffffff99d60512>] pstore_dump+0x72/0x330
    |CPU: 26 PID: 2236 Comm: sig-xstate-bum Tainted: G      D           4.20.0-rc3 #45
    |Call Trace:
    | dump_stack+0x4f/0x6a
    | ___might_sleep.cold.91+0xd3/0xe4
    | __might_sleep+0x50/0x90
    | wait_for_completion+0x32/0x130
    | virt_efi_query_variable_info+0x14e/0x160
    | efi_query_variable_store+0x51/0x1a0
    | efivar_entry_set_safe+0xa3/0x1b0
    | efi_pstore_write+0x109/0x140
    | pstore_dump+0x11c/0x330
    | kmsg_dump+0xa4/0xd0
    | oops_exit+0x22/0x30
    ...
    Reported-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
    Fixes: 21b3ddd3 ("efi: Don't use spinlocks for efi vars")
    Signed-off-by: default avatarKees Cook <keescook@chromium.org>
    ea84b580
platform.c 18.9 KB