From: Jiri Slaby <jslaby@suse.cz>
To: linux-kernel@vger.kernel.org
Cc: tj@kernel.org, rostedt@goodmis.org, mingo@redhat.com,
akpm@linux-foundation.org, andi@firstfloor.org,
paulmck@linux.vnet.ibm.com, pavel@ucw.cz, jirislaby@gmail.com,
Vojtech Pavlik <vojtech@suse.cz>, Michael Matz <matz@suse.de>,
Jiri Kosina <jkosina@suse.cz>, Jiri Slaby <jslaby@suse.cz>
Subject: [PATCH -repost 18/21] kgr: fix race of stub and patching
Date: Wed, 25 Jun 2014 13:07:12 +0200 [thread overview]
Message-ID: <1403694435-3180-18-git-send-email-jslaby@suse.cz> (raw)
In-Reply-To: <1403694435-3180-1-git-send-email-jslaby@suse.cz>
While we are patching, we set up a stub which refers to
kgr_in_progress of a process. The stub can be called immediately when
set up, but we set the flag even after done with patching in
kgr_handle_processes. This is obviously too late, so set the flag
before we start patching, but after we check that no other patching is
in progress -- we would interfere otherwise.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
---
kernel/kgraft.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/kernel/kgraft.c b/kernel/kgraft.c
index 121faefcbb28..5ec0c1abe0d6 100644
--- a/kernel/kgraft.c
+++ b/kernel/kgraft.c
@@ -124,14 +124,22 @@ static void kgr_work_fn(struct work_struct *work)
mutex_unlock(&kgr_in_progress_lock);
}
-static void kgr_handle_processes(void)
+static void kgr_mark_processes(void)
{
struct task_struct *p;
read_lock(&tasklist_lock);
- for_each_process(p) {
+ for_each_process(p)
kgr_mark_task_in_progress(p);
+ read_unlock(&tasklist_lock);
+}
+static void kgr_handle_processes(void)
+{
+ struct task_struct *p;
+
+ read_lock(&tasklist_lock);
+ for_each_process(p) {
/* wake up kthreads, they will clean the progress flag */
if (!p->mm) {
/*
@@ -333,6 +341,8 @@ int kgr_start_patching(struct kgr_patch *patch)
goto unlock_free;
}
+ kgr_mark_processes();
+
for (patch_fun = patch->patches; *patch_fun; patch_fun++) {
ret = kgr_patch_code(patch, *patch_fun, false);
/*
--
2.0.0
next prev parent reply other threads:[~2014-06-25 11:09 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-25 11:06 [PATCH -repost 01/21] ftrace: Add function to find fentry of function Jiri Slaby
2014-06-25 11:06 ` [PATCH -repost 02/21] ftrace: Make ftrace_is_dead available globally Jiri Slaby
2014-06-25 11:06 ` [PATCH -repost 03/21] kgr: initial code Jiri Slaby
2014-06-25 11:06 ` [PATCH -repost 04/21] kgr: add testing kgraft patch Jiri Slaby
2014-06-25 11:06 ` [PATCH -repost 05/21] kgr: update Kconfig documentation Jiri Slaby
2014-06-25 12:42 ` One Thousand Gnomes
2014-06-26 8:25 ` Jiri Slaby
2014-06-26 8:34 ` Jiri Kosina
2014-06-27 19:18 ` Pavel Machek
2014-07-04 9:14 ` Jiri Slaby
2014-07-04 10:35 ` Pavel Machek
2014-07-05 19:47 ` Jiri Kosina
2014-07-06 12:35 ` Pavel Machek
2014-06-25 11:07 ` [PATCH -repost 06/21] kgr: add Documentation Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 07/21] kgr: trigger the first check earlier Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 08/21] kgr: sched.h, introduce kgr_task_safe helper Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 09/21] kgr: mark task_safe in some kthreads Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 10/21] kgr: kthreads support Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 11/21] kgr: handle irqs Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 12/21] kgr: add MAINTAINERS entry Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 13/21] kgr: x86: refuse to build without fentry support Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 14/21] kgr: add procfs interface for per-process 'kgr_in_progress' Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 15/21] kgr: make a per-process 'in progress' flag a single bit Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 16/21] kgr: add support for missing functions Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 17/21] kgr: exercise non-present function Jiri Slaby
2014-06-25 11:07 ` Jiri Slaby [this message]
2014-06-25 11:07 ` [PATCH -repost 19/21] kgr: expose global 'in_progress' state through procfs Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 20/21] kgr: rephrase the "kGraft failed" message Jiri Slaby
2014-06-25 11:07 ` [PATCH -repost 21/21] kgr: x86: optimize handling of CPU-bound tasks Jiri Slaby
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