BPF Archive on lore.kernel.org
 help / color / Atom feed
From: Masami Hiramatsu <mhiramat@kernel.org>
To: Brendan Gregg <brendan.d.gregg@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Alexei Starovoitov <ast@kernel.org>
Cc: mhiramat@kernel.org, Ingo Molnar <mingo@kernel.org>,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	Daniel Borkmann <daniel@iogearbox.net>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	paulmck@kernel.org, joel@joelfernandes.org,
	"Naveen N . Rao" <naveen.n.rao@linux.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Subject: [RFT PATCH 07/13] kprobes: Use normal list traversal API if a mutex is held
Date: Thu, 16 Jan 2020 23:45:23 +0900
Message-ID: <157918592332.29301.1564446199611592837.stgit@devnote2> (raw)
In-Reply-To: <157918584866.29301.6941815715391411338.stgit@devnote2>

Use normal list traversal API instead of rcu_read_lock,
RCU list traversal and rcu_read_unlock pair if a mutex
which protects the list is held in the methods of
kprobe_insn_cache.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/kprobes.c |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 848c14e92ccc..09b0e33bc845 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -141,8 +141,7 @@ kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
 	/* Since the slot array is not protected by rcu, we need a mutex */
 	mutex_lock(&c->mutex);
  retry:
-	rcu_read_lock();
-	list_for_each_entry_rcu(kip, &c->pages, list) {
+	list_for_each_entry(kip, &c->pages, list) {
 		if (kip->nused < slots_per_page(c)) {
 			int i;
 			for (i = 0; i < slots_per_page(c); i++) {
@@ -150,7 +149,6 @@ kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
 					kip->slot_used[i] = SLOT_USED;
 					kip->nused++;
 					slot = kip->insns + (i * c->insn_size);
-					rcu_read_unlock();
 					goto out;
 				}
 			}
@@ -159,7 +157,6 @@ kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
 			WARN_ON(1);
 		}
 	}
-	rcu_read_unlock();
 
 	/* If there are any garbage slots, collect it and try again. */
 	if (c->nr_garbage && collect_garbage_slots(c) == 0)
@@ -244,8 +241,7 @@ void __free_insn_slot(struct kprobe_insn_cache *c,
 	long idx;
 
 	mutex_lock(&c->mutex);
-	rcu_read_lock();
-	list_for_each_entry_rcu(kip, &c->pages, list) {
+	list_for_each_entry(kip, &c->pages, list) {
 		idx = ((long)slot - (long)kip->insns) /
 			(c->insn_size * sizeof(kprobe_opcode_t));
 		if (idx >= 0 && idx < slots_per_page(c))
@@ -255,7 +251,6 @@ void __free_insn_slot(struct kprobe_insn_cache *c,
 	WARN_ON(1);
 	kip = NULL;
 out:
-	rcu_read_unlock();
 	/* Mark and sweep: this may sleep */
 	if (kip) {
 		/* Check double free */


  parent reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 14:44 [RFT PATCH 00/13] tracing: kprobes: Introduce async unregistration Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 01/13] kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 02/13] kprobes: Remove redundant arch_disarm_kprobe() call Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 03/13] kprobes: Postpone optimizer until a bunch of probes (un)registered Masami Hiramatsu
2020-01-16 14:44 ` [RFT PATCH 04/13] kprobes: Make optimizer delay to 1 second Masami Hiramatsu
2020-01-22  0:29   ` Steven Rostedt
2020-01-22  7:23     ` Masami Hiramatsu
2020-01-22 12:11       ` Steven Rostedt
2020-01-22 13:12         ` Masami Hiramatsu
2020-01-22 16:54           ` Paul E. McKenney
2020-01-23  1:33             ` Masami Hiramatsu
2020-01-23  2:26               ` Paul E. McKenney
2020-01-23  6:13                 ` Masami Hiramatsu
2020-01-23 10:03                   ` Paul E. McKenney
2020-01-16 14:45 ` [RFT PATCH 05/13] tracing/kprobe: Use call_rcu to defer freeing event_file_link Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 06/13] kprobes: Enable kprobe-booster with CONFIG_PREEMPT=y Masami Hiramatsu
2020-01-16 14:45 ` Masami Hiramatsu [this message]
2020-01-16 14:45 ` [RFT PATCH 08/13] kprobes: Use workqueue for reclaiming kprobe insn cache pages Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 09/13] kprobes: Free kprobe_insn_page asynchronously Masami Hiramatsu
2020-01-16 14:45 ` [RFT PATCH 10/13] kprobes: Make free_*insn_slot() mutex-less Masami Hiramatsu
2020-01-16 14:46 ` [RFT PATCH 11/13] kprobes: Add asynchronous unregistration APIs Masami Hiramatsu
2020-01-16 14:46 ` [RFT PATCH 12/13] tracing/kprobe: Free probe event asynchronously Masami Hiramatsu
2020-01-16 14:46 ` [RFT PATCH 13/13] tracing/kprobe: perf_event: Remove local kprobe " Masami Hiramatsu

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=157918592332.29301.1564446199611592837.stgit@devnote2 \
    --to=mhiramat@kernel.org \
    --cc=acme@kernel.org \
    --cc=anil.s.keshavamurthy@intel.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=brendan.d.gregg@gmail.com \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=joel@joelfernandes.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=naveen.n.rao@linux.ibm.com \
    --cc=paulmck@kernel.org \
    --cc=rostedt@goodmis.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 bpf bpf/ https://lore.kernel.org/bpf \
		bpf@vger.kernel.org
	public-inbox-index bpf

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.bpf


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git