uprobes: kill xol_area->slot_count

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Add the new helper, xol_get_slot_nr() which does
find_first_zero_bit() + test_and_set_bit().

xol_take_insn_slot() can wait for the "xol_get_slot_nr() < UINSNS_PER_PAGE"
event instead of "area->slot_count < UINSNS_PER_PAGE".

So we can kill area->slot_count and avoid atomic_inc() + atomic_dec(), this
simplifies the code and can slightly improve the performance.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20241001142458.GA13629@redhat.com

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Oleg Nesterov 2024-10-01 16:24:59 +02:00 • committed by Peter Zijlstra

parent c16e2fdd74

commit 7a166094bd

1 changed files with 15 additions and 14 deletions

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kernel/events/uprobes.c

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