Andrea Parri 8d3ab1ccc0 uprobes: Fix handle_swbp() vs. unregister() + register() race once more ... commit 09d3f015d1 upstream. Commit: 142b18ddc8 ("uprobes: Fix handle_swbp() vs unregister() + register() race") added the UPROBE_COPY_INSN flag, and corresponding smp_wmb() and smp_rmb() memory barriers, to ensure that handle_swbp() uses fully-initialized uprobes only. However, the smp_rmb() is mis-placed: this barrier should be placed after handle_swbp() has tested for the flag, thus guaranteeing that (program-order) subsequent loads from the uprobe can see the initial stores performed by prepare_uprobe(). Move the smp_rmb() accordingly. Also amend the comments associated to the two memory barriers to indicate their actual locations. Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: stable@kernel.org Fixes: 142b18ddc8 ("uprobes: Fix handle_swbp() vs unregister() + register() race") Link: http://lkml.kernel.org/r/20181122161031.15179-1-andrea.parri@amarulasolutions.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-12-08 13:03:36 +01:00
..
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
callchain.c	perf: Remove superfluous allocation error check	2018-05-16 10:10:24 +02:00
core.c	perf/ring_buffer: Prevent concurent ring buffer access	2018-11-04 14:52:40 +01:00
hw_breakpoint.c	perf/hwbp: Simplify the perf-hwbp code, fix documentation	2018-04-08 14:26:27 +02:00
internal.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
ring_buffer.c	perf/core: Fix possible Spectre-v1 indexing for ->aux_pages[]	2018-05-16 10:10:31 +02:00
uprobes.c	uprobes: Fix handle_swbp() vs. unregister() + register() race once more	2018-12-08 13:03:36 +01:00