From: Peter Zijlstra <peterz@infradead.org>
To: gor@linux.ibm.com, jpoimboe@redhat.com, jikos@kernel.org,
mbenes@suse.cz, pmladek@suse.com, mingo@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
joe.lawrence@redhat.com, fweisbec@gmail.com, tglx@linutronix.de,
hca@linux.ibm.com, svens@linux.ibm.com, sumanthk@linux.ibm.com,
live-patching@vger.kernel.org, paulmck@kernel.org,
rostedt@goodmis.org, x86@kernel.org
Subject: [PATCH v2 03/11] sched,livepatch: Use task_call_func()
Date: Wed, 29 Sep 2021 17:17:26 +0200 [thread overview]
Message-ID: <20210929152428.709906138@infradead.org> (raw)
In-Reply-To: 20210929151723.162004989@infradead.org
Instead of frobbing around with scheduler internals, use the shiny new
task_call_func() interface.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/livepatch/transition.c | 90 ++++++++++++++++++++----------------------
1 file changed, 44 insertions(+), 46 deletions(-)
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -13,7 +13,6 @@
#include "core.h"
#include "patch.h"
#include "transition.h"
-#include "../sched/sched.h"
#define MAX_STACK_ENTRIES 100
#define STACK_ERR_BUF_SIZE 128
@@ -240,7 +239,7 @@ static int klp_check_stack_func(struct k
* Determine whether it's safe to transition the task to the target patch state
* by looking for any to-be-patched or to-be-unpatched functions on its stack.
*/
-static int klp_check_stack(struct task_struct *task, char *err_buf)
+static int klp_check_stack(struct task_struct *task, const char **oldname)
{
static unsigned long entries[MAX_STACK_ENTRIES];
struct klp_object *obj;
@@ -248,12 +247,8 @@ static int klp_check_stack(struct task_s
int ret, nr_entries;
ret = stack_trace_save_tsk_reliable(task, entries, ARRAY_SIZE(entries));
- if (ret < 0) {
- snprintf(err_buf, STACK_ERR_BUF_SIZE,
- "%s: %s:%d has an unreliable stack\n",
- __func__, task->comm, task->pid);
- return ret;
- }
+ if (ret < 0)
+ return -EINVAL;
nr_entries = ret;
klp_for_each_object(klp_transition_patch, obj) {
@@ -262,11 +257,8 @@ static int klp_check_stack(struct task_s
klp_for_each_func(obj, func) {
ret = klp_check_stack_func(func, entries, nr_entries);
if (ret) {
- snprintf(err_buf, STACK_ERR_BUF_SIZE,
- "%s: %s:%d is sleeping on function %s\n",
- __func__, task->comm, task->pid,
- func->old_name);
- return ret;
+ *oldname = func->old_name;
+ return -EADDRINUSE;
}
}
}
@@ -274,6 +266,22 @@ static int klp_check_stack(struct task_s
return 0;
}
+static int klp_check_and_switch_task(struct task_struct *task, void *arg)
+{
+ int ret;
+
+ if (task_curr(task))
+ return -EBUSY;
+
+ ret = klp_check_stack(task, arg);
+ if (ret)
+ return ret;
+
+ clear_tsk_thread_flag(task, TIF_PATCH_PENDING);
+ task->patch_state = klp_target_state;
+ return 0;
+}
+
/*
* Try to safely switch a task to the target patch state. If it's currently
* running, or it's sleeping on a to-be-patched or to-be-unpatched function, or
@@ -281,13 +289,8 @@ static int klp_check_stack(struct task_s
*/
static bool klp_try_switch_task(struct task_struct *task)
{
- static char err_buf[STACK_ERR_BUF_SIZE];
- struct rq *rq;
- struct rq_flags flags;
+ const char *old_name;
int ret;
- bool success = false;
-
- err_buf[0] = '\0';
/* check if this task has already switched over */
if (task->patch_state == klp_target_state)
@@ -305,36 +308,31 @@ static bool klp_try_switch_task(struct t
* functions. If all goes well, switch the task to the target patch
* state.
*/
- rq = task_rq_lock(task, &flags);
+ ret = task_call_func(task, klp_check_and_switch_task, &old_name);
+ switch (ret) {
+ case 0: /* success */
+ break;
- if (task_running(rq, task) && task != current) {
- snprintf(err_buf, STACK_ERR_BUF_SIZE,
- "%s: %s:%d is running\n", __func__, task->comm,
- task->pid);
- goto done;
+ case -EBUSY: /* klp_check_and_switch_task() */
+ pr_debug("%s: %s:%d is running\n",
+ __func__, task->comm, task->pid);
+ break;
+ case -EINVAL: /* klp_check_and_switch_task() */
+ pr_debug("%s: %s:%d has an unreliable stack\n",
+ __func__, task->comm, task->pid);
+ break;
+ case -EADDRINUSE: /* klp_check_and_switch_task() */
+ pr_debug("%s: %s:%d is sleeping on function %s\n",
+ __func__, task->comm, task->pid, old_name);
+ break;
+
+ default:
+ pr_debug("%s: Unknown error code (%d) when trying to switch %s:%d\n",
+ __func__, ret, task->comm, task->pid);
+ break;
}
- ret = klp_check_stack(task, err_buf);
- if (ret)
- goto done;
-
- success = true;
-
- clear_tsk_thread_flag(task, TIF_PATCH_PENDING);
- task->patch_state = klp_target_state;
-
-done:
- task_rq_unlock(rq, task, &flags);
-
- /*
- * Due to console deadlock issues, pr_debug() can't be used while
- * holding the task rq lock. Instead we have to use a temporary buffer
- * and print the debug message after releasing the lock.
- */
- if (err_buf[0] != '\0')
- pr_debug("%s", err_buf);
-
- return success;
+ return !ret;
}
/*
next prev parent reply other threads:[~2021-09-29 15:58 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 15:17 [PATCH v2 00/11] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL Peter Zijlstra
2021-09-29 15:17 ` [PATCH v2 01/11] sched: Improve try_invoke_on_locked_down_task() Peter Zijlstra
2021-10-09 10:07 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-09-29 15:17 ` [PATCH v2 02/11] sched,rcu: Rework try_invoke_on_locked_down_task() Peter Zijlstra
2021-10-09 10:07 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-09-29 15:17 ` Peter Zijlstra [this message]
2021-10-05 11:40 ` [PATCH v2 03/11] sched,livepatch: Use task_call_func() Petr Mladek
2021-10-05 14:03 ` Peter Zijlstra
2021-10-06 8:59 ` Miroslav Benes
2021-10-09 10:07 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-09-29 15:17 ` [PATCH v2 04/11] sched: Simplify wake_up_*idle*() Peter Zijlstra
2021-10-09 10:07 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-10-13 14:32 ` [PATCH v2 04/11] " Qian Cai
2021-10-19 3:47 ` Qian Cai
2021-10-19 8:56 ` Peter Zijlstra
2021-10-19 9:10 ` Peter Zijlstra
2021-10-19 15:32 ` Qian Cai
2021-10-19 15:50 ` Peter Zijlstra
2021-10-19 19:22 ` Qian Cai
2021-10-19 20:27 ` Peter Zijlstra
[not found] ` <CGME20211022134630eucas1p2e79e2816587d182c580459d567c1f2a9@eucas1p2.samsung.com>
2021-10-22 13:46 ` Marek Szyprowski
2021-09-29 15:17 ` [PATCH v2 05/11] sched,livepatch: Use wake_up_if_idle() Peter Zijlstra
2021-10-05 12:00 ` Petr Mladek
2021-10-06 9:16 ` Miroslav Benes
2021-10-07 9:18 ` Vasily Gorbik
2021-10-07 10:02 ` Peter Zijlstra
2021-10-13 19:37 ` Arnd Bergmann
2021-10-14 10:42 ` Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 06/11] context_tracking: Prefix user_{enter,exit}*() Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 07/11] context_tracking: Add an atomic sequence/state count Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 08/11] context_tracking,rcu: Replace RCU dynticks counter with context_tracking Peter Zijlstra
2021-09-29 18:37 ` Paul E. McKenney
2021-09-29 19:09 ` Peter Zijlstra
2021-09-29 19:11 ` Peter Zijlstra
2021-09-29 19:13 ` Peter Zijlstra
2021-09-29 19:24 ` Peter Zijlstra
2021-09-29 19:45 ` Paul E. McKenney
2021-09-29 18:54 ` Peter Zijlstra
2021-09-29 15:17 ` [RFC][PATCH v2 09/11] context_tracking,livepatch: Dont disturb NOHZ_FULL Peter Zijlstra
2021-10-06 8:12 ` Petr Mladek
2021-10-06 9:04 ` Peter Zijlstra
2021-10-06 10:29 ` Petr Mladek
2021-10-06 11:41 ` Peter Zijlstra
2021-10-06 11:48 ` Miroslav Benes
2021-09-29 15:17 ` [RFC][PATCH v2 10/11] livepatch: Remove klp_synchronize_transition() Peter Zijlstra
2021-10-06 12:30 ` Petr Mladek
2021-09-29 15:17 ` [RFC][PATCH v2 11/11] context_tracking,x86: Fix text_poke_sync() vs NOHZ_FULL Peter Zijlstra
2021-10-21 18:39 ` Marcelo Tosatti
2021-10-21 18:40 ` Marcelo Tosatti
2021-10-21 19:25 ` Peter Zijlstra
2021-10-21 19:57 ` Marcelo Tosatti
2021-10-21 20:18 ` Peter Zijlstra
2021-10-26 18:19 ` Marcelo Tosatti
2021-10-26 19:38 ` Peter Zijlstra
2021-09-29 18:03 ` [PATCH v2 00/11] sched,rcu,context_tracking,livepatch: Improve livepatch task transitions for idle and NOHZ_FULL Paul E. McKenney
2021-10-09 10:07 ` [tip: sched/core] sched,livepatch: Use wake_up_if_idle() tip-bot2 for Peter Zijlstra
2021-10-14 11:16 ` tip-bot2 for Peter Zijlstra
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