x86/rtc: Don't recursively acquire rtc_lock

A deadlock was introduced on x86 in commit ef68c8f87ed1 ("x86:
Serialize EFI time accesses on rtc_lock") because efi_get_time()
and friends can be called with rtc_lock already held by
read_persistent_time(), e.g.:

 timekeeping_init()
    read_persistent_clock()     <-- acquire rtc_lock
        efi_get_time()
            phys_efi_get_time() <-- acquire rtc_lock <DEADLOCK>

To fix this let's push the locking down into the get_wallclock()
and set_wallclock() implementations.  Only the clock
implementations that access the x86 RTC directly need to acquire
rtc_lock, so it makes sense to push the locking down into the
rtc, vrtc and efi code.

The virtualization implementations don't require rtc_lock to be
held because they provide their own serialization.

Signed-off-by: Matt Fleming <[email protected]>
Acked-by: Jan Beulich <[email protected]>
Acked-by: Avi Kivity <[email protected]> [for the virtualization aspect]
Cc: "H. Peter Anvin" <[email protected]>
Cc: Zhang Rui <[email protected]>
Cc: Josh Boyer <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions