From:   Byungchul Park <max.byungchul.park@gmail.com>
To:     linux-kernel@vger.kernel.org
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Subject: [PATCH v9 13/25] dept: Distinguish each work from another
Date:   Tue, 31 Jan 2023 17:39:42 +0900
Message-Id: <1675154394-25598-14-git-send-email-max.byungchul.park@gmail.com>
In-Reply-To: <1675154394-25598-1-git-send-email-max.byungchul.park@gmail.com>
References: <1675154394-25598-1-git-send-email-max.byungchul.park@gmail.com>
Precedence: bulk

Workqueue already provides concurrency control. By that, any wait in a
work doesn't prevents events in other works with the control enabled.
Thus, each work would better be considered a different context.

So let Dept assign a different context id to each work.

Signed-off-by: Byungchul Park <max.byungchul.park@gmail.com>
---
 include/linux/dept.h     |  2 ++
 kernel/dependency/dept.c | 10 ++++++++++
 kernel/workqueue.c       |  3 +++
 3 files changed, 15 insertions(+)

diff --git a/include/linux/dept.h b/include/linux/dept.h
index f62c7b6..d9ca9dd 100644
--- a/include/linux/dept.h
+++ b/include/linux/dept.h
@@ -515,6 +515,7 @@ struct dept_task {
 extern void dept_sched_enter(void);
 extern void dept_sched_exit(void);
 extern void dept_kernel_enter(void);
+extern void dept_work_enter(void);
 
 static inline void dept_ecxt_enter_nokeep(struct dept_map *m)
 {
@@ -567,6 +568,7 @@ static inline void dept_ecxt_enter_nokeep(struct dept_map *m)
 #define dept_sched_enter()				do { } while (0)
 #define dept_sched_exit()				do { } while (0)
 #define dept_kernel_enter()				do { } while (0)
+#define dept_work_enter()				do { } while (0)
 #define dept_ecxt_enter_nokeep(m)			do { } while (0)
 #define dept_key_init(k)				do { (void)(k); } while (0)
 #define dept_key_destroy(k)				do { (void)(k); } while (0)
diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c
index dd90746..1f1aca4 100644
--- a/kernel/dependency/dept.c
+++ b/kernel/dependency/dept.c
@@ -1977,6 +1977,16 @@ void dept_hardirqs_off_ip(unsigned long ip)
 }
 EXPORT_SYMBOL_GPL(dept_hardirqs_off_ip);
 
+/*
+ * Assign a different context id to each work.
+ */
+void dept_work_enter(void)
+{
+	struct dept_task *dt = dept_task();
+
+	dt->cxt_id[DEPT_CXT_PROCESS] += 1UL << DEPT_CXTS_NR;
+}
+
 void dept_kernel_enter(void)
 {
 	struct dept_task *dt = dept_task();
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 07895de..69c4f46 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -51,6 +51,7 @@
 #include <linux/sched/isolation.h>
 #include <linux/nmi.h>
 #include <linux/kvm_para.h>
+#include <linux/dept.h>
 
 #include "workqueue_internal.h"
 
@@ -2199,6 +2200,8 @@ static void process_one_work(struct worker *worker, struct work_struct *work)
 
 	lockdep_copy_map(&lockdep_map, &work->lockdep_map);
 #endif
+	dept_work_enter();
+
 	/* ensure we're on the correct CPU */
 	WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
 		     raw_smp_processor_id() != pool->cpu);
-- 
1.9.1