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| author | Chris Metcalf <cmetcalf@tilera.com> | 2013-09-26 13:24:53 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-13 14:51:08 -0700 |
| commit | a9f1434b8e47776e2b6d42a5556516209f5ba3ae (patch) | |
| tree | 3a4b2e1d35eb04faa988be590678841ba0f7d218 /fs/btrfs | |
| parent | b8a3fdb8cfff87da926b868c3263a8a51c02af47 (diff) | |
| download | kernel_samsung_smdk4412-a9f1434b8e47776e2b6d42a5556516209f5ba3ae.zip kernel_samsung_smdk4412-a9f1434b8e47776e2b6d42a5556516209f5ba3ae.tar.gz kernel_samsung_smdk4412-a9f1434b8e47776e2b6d42a5556516209f5ba3ae.tar.bz2 | |
tile: use a more conservative __my_cpu_offset in CONFIG_PREEMPT
commit f862eefec0b68e099a9fa58d3761ffb10bad97e1 upstream.
It turns out the kernel relies on barrier() to force a reload of the
percpu offset value. Since we can't easily modify the definition of
barrier() to include "tp" as an output register, we instead provide a
definition of __my_cpu_offset as extended assembly that includes a fake
stack read to hazard against barrier(), forcing gcc to know that it
must reread "tp" and recompute anything based on "tp" after a barrier.
This fixes observed hangs in the slub allocator when we are looping
on a percpu cmpxchg_double.
A similar fix for ARMv7 was made in June in change 509eb76ebf97.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/btrfs')
0 files changed, 0 insertions, 0 deletions