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From: tip-bot for Kan Liang <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: ak@linux.intel.com, acme@redhat.com, a.p.zijlstra@chello.nl,
	kan.liang@intel.com, hpa@zytor.com, mingo@kernel.org,
	tglx@linutronix.de, linux-kernel@vger.kernel.org,
	xiakaixu@huawei.com
Subject: [tip:perf/core] Revert "perf: Remove the extra validity check on nr_pages"
Date: Mon, 2 Mar 2015 22:26:46 -0800	[thread overview]
Message-ID: <tip-2ed11312eb19506c027e7cac039994ad42a9cb2c@git.kernel.org> (raw)
In-Reply-To: <1425280466-7830-1-git-send-email-kan.liang@intel.com>

Commit-ID:  2ed11312eb19506c027e7cac039994ad42a9cb2c
Gitweb:     http://git.kernel.org/tip/2ed11312eb19506c027e7cac039994ad42a9cb2c
Author:     Kan Liang <kan.liang@intel.com>
AuthorDate: Mon, 2 Mar 2015 02:14:26 -0500
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 2 Mar 2015 18:25:38 -0300

Revert "perf: Remove the extra validity check on nr_pages"

This reverts commit 74390aa55678 ("perf: Remove the extra validity check
on nr_pages")

nr_pages equals to number of pages - 1 in perf_mmap. So nr_pages = 0 is
valid.

So the nr_pages != 0 && !is_power_of_2(nr_pages) are all
needed for checking. Otherwise, for example, perf test 6 failed.

 # perf test 6
  6: x86 rdpmc test                                         :Error:
 mmap() syscall returned with (Invalid argument)
 FAILED!

Signed-off-by: Kan Liang <kan.liang@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1425280466-7830-1-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index af924bc..8bb20cc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4446,7 +4446,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 	 * If we have rb pages ensure they're a power-of-two number, so we
 	 * can do bitmasks instead of modulo.
 	 */
-	if (!is_power_of_2(nr_pages))
+	if (nr_pages != 0 && !is_power_of_2(nr_pages))
 		return -EINVAL;
 
 	if (vma_size != PAGE_SIZE * (1 + nr_pages))

  parent reply	other threads:[~2015-03-03  6:27 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-02  7:14 [PATCH 1/1] " kan.liang
2015-03-02 21:03 ` Arnaldo Carvalho de Melo
2015-03-03  6:26 ` tip-bot for Kan Liang [this message]
2015-03-03  8:44   ` [tip:perf/core] " Ingo Molnar
2015-03-03 20:04     ` Liang, Kan
2015-03-04  4:46       ` Ingo Molnar
2015-03-04 14:06         ` Liang, Kan
2015-03-04 20:28           ` Ingo Molnar

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