sunrpc: remove xpt_pool

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The xpt_pool field is only used for reporting BUGs.
And it isn't used correctly.

In particular, when it is cleared in svc_xprt_received before
XPT_BUSY is cleared, there is no guarantee that either the
compiler or the CPU might not re-order to two assignments, just
setting xpt_pool to NULL after XPT_BUSY is cleared.

If a different cpu were running svc_xprt_enqueue at this moment,
it might see XPT_BUSY clear and then xpt_pool non-NULL, and
so BUG.

This could be fixed by calling
  smp_mb__before_clear_bit()
before the clear_bit.  However as xpt_pool isn't really used,
it seems safest to simply remove xpt_pool.

Another alternate would be to change the clear_bit to
clear_bit_unlock, and the test_and_set_bit to test_and_set_bit_lock.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

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This commit is contained in:

NeilBrown 2010-11-15 11:27:01 +11:00 • committed by J. Bruce Fields

parent 18b631f838

commit 7c96aef759

2 changed files with 0 additions and 6 deletions

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1

include/linux/sunrpc/svc_xprt.h

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5

net/sunrpc/svc_xprt.c

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