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[v3,0/2] kexec, panic: Making crash_kexec() NMI safe

Message ID 20220630172041.4100123-1-vschneid@redhat.com
Headers show
Series kexec, panic: Making crash_kexec() NMI safe | expand

Message

Valentin Schneider June 30, 2022, 5:20 p.m. UTC 
Hi folks,

Here's v3 where we now completely get rid of kexec_mutex.

o Patch 1 makes sure all kexec_mutex acquisitions are trylocks. This prevents
  having to add any while(atomic_cmpxchg()) loops which I'd really hate to see
  here. If that can't be done then I think we're better off with the combined
  mutex+atomic var approach.
o Patch 2 does the mutex -> atomic var switch.

Revisions
=========

v2 -> v3
++++++++

o Dropped kexec_mutex entirely and made the atomic variable the one true lock
  for kexec (Eric)

v1 -> v2
++++++++

o Changed from Peterson-like synchronization to simpler atomic_cmpxchg
  (Petr)
o Slightly reworded changelog
o Added Fixes: tag. Technically should be up to since kexec can happen
  in an NMI, but that isn't such a clear target

Cheers,
Valentin

Valentin Schneider (2):
  kexec: Turn all kexec_mutex acquisitions into trylocks
  panic, kexec: Make __crash_kexec() NMI safe

 include/linux/kexec.h   |  2 +-
 kernel/kexec.c          | 11 ++++-------
 kernel/kexec_core.c     | 28 ++++++++++++++++------------
 kernel/kexec_file.c     |  4 ++--
 kernel/kexec_internal.h | 15 ++++++++++++++-
 kernel/ksysfs.c         |  7 ++++++-
 6 files changed, 43 insertions(+), 24 deletions(-)

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2.31.1