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From: ebiederm@xmission.com (Eric W. Biederman)
To: <linux-kernel@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Jann Horn <jannh@google.com>,
	Vasiliy Kulikov <segoon@openwall.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Bernd Edlinger <bernd.edlinger@hotmail.de>,
	Oleg Nesterov <oleg@redhat.com>,
	Christopher Yeoh <cyeoh@au1.ibm.com>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Sargun Dhillon <sargun@sargun.me>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: [PATCH 2/3] rwsem: Implement down_read_interruptible
Date: Thu, 03 Dec 2020 14:11:13 -0600	[thread overview]
Message-ID: <87k0tybqfy.fsf@x220.int.ebiederm.org> (raw)
In-Reply-To: <87tut2bqik.fsf@x220.int.ebiederm.org> (Eric W. Biederman's message of "Thu, 03 Dec 2020 14:09:39 -0600")


In preparation for converting exec_update_mutex to a rwsem so that
multiple readers can execute in parallel and not deadlock, add
down_read_interruptible.  This is needed for perf_event_open to be
converted (with no semantic changes) from working on a mutex to
wroking on a rwsem.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 include/linux/rwsem.h  |  1 +
 kernel/locking/rwsem.c | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 13021b08b2ed..4c715be48717 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -123,6 +123,7 @@ static inline int rwsem_is_contended(struct rw_semaphore *sem)
  * lock for reading
  */
 extern void down_read(struct rw_semaphore *sem);
+extern int __must_check down_read_interruptible(struct rw_semaphore *sem);
 extern int __must_check down_read_killable(struct rw_semaphore *sem);
 
 /*
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 54d11cb97551..a163542d178e 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1345,6 +1345,18 @@ static inline void __down_read(struct rw_semaphore *sem)
 	}
 }
 
+static inline int __down_read_interruptible(struct rw_semaphore *sem)
+{
+	if (!rwsem_read_trylock(sem)) {
+		if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_INTERRUPTIBLE)))
+			return -EINTR;
+		DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
+	} else {
+		rwsem_set_reader_owned(sem);
+	}
+	return 0;
+}
+
 static inline int __down_read_killable(struct rw_semaphore *sem)
 {
 	if (!rwsem_read_trylock(sem)) {
@@ -1495,6 +1507,20 @@ void __sched down_read(struct rw_semaphore *sem)
 }
 EXPORT_SYMBOL(down_read);
 
+int __sched down_read_interruptible(struct rw_semaphore *sem)
+{
+	might_sleep();
+	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
+
+	if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_interruptible)) {
+		rwsem_release(&sem->dep_map, _RET_IP_);
+		return -EINTR;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(down_read_interruptible);
+
 int __sched down_read_killable(struct rw_semaphore *sem)
 {
 	might_sleep();
-- 
2.25.0


  parent reply	other threads:[~2020-12-03 20:12 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03 20:09 [PATCH 0/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-03 20:10 ` [PATCH 1/3] rwsem: Implement down_read_killable_nested Eric W. Biederman
2020-12-04  1:58   ` Waiman Long
2020-12-09 18:38   ` [tip: locking/core] " tip-bot2 for Eric W. Biederman
2020-12-03 20:11 ` Eric W. Biederman [this message]
2020-12-04  1:59   ` [PATCH 2/3] rwsem: Implement down_read_interruptible Waiman Long
2020-12-07  9:02     ` Peter Zijlstra
2020-12-07 15:33       ` Waiman Long
2020-12-07 16:58         ` David Laight
2020-12-07 19:02           ` Waiman Long
2020-12-08  9:12             ` David Laight
2020-12-08 12:32               ` Peter Zijlstra
2020-12-08 13:13                 ` David Laight
2020-12-08 15:34               ` Waiman Long
2020-12-08 16:23                 ` David Laight
2020-12-07 15:56       ` Eric W. Biederman
2020-12-08 14:52         ` Peter Zijlstra
2020-12-08 18:27           ` Eric W. Biederman
2020-12-09 18:36             ` Peter Zijlstra
2020-12-10 19:33               ` Eric W. Biederman
2020-12-11  8:16                 ` Peter Zijlstra
2020-12-09 18:38       ` [tip: locking/core] locking/rwsem: Introduce rwsem_write_trylock() tip-bot2 for Peter Zijlstra
2020-12-09 18:38       ` [tip: locking/core] locking/rwsem: Fold __down_{read,write}*() tip-bot2 for Peter Zijlstra
2020-12-09 18:38       ` [tip: locking/core] locking/rwsem: Better collate rwsem_read_trylock() tip-bot2 for Peter Zijlstra
2020-12-09 18:38   ` [tip: locking/core] rwsem: Implement down_read_interruptible tip-bot2 for Eric W. Biederman
2020-12-03 20:12 ` [PATCH 3/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-04 16:08   ` Bernd Edlinger
2020-12-04 17:21     ` Linus Torvalds
2020-12-04 19:34       ` Eric W. Biederman
2020-12-04 20:10         ` Linus Torvalds
2020-12-04 20:30           ` Bernd Edlinger
2020-12-04 20:48             ` Linus Torvalds
2020-12-04 21:48               ` Davidlohr Bueso
2020-12-05 18:05                 ` Eric W. Biederman
2020-12-07  9:15                   ` Peter Zijlstra
2020-12-07  9:09               ` Peter Zijlstra
2020-12-07 18:40                 ` Linus Torvalds
2020-12-08  8:34                   ` [PATCH] perf: Break deadlock involving exec_update_mutex Peter Zijlstra
2020-12-08 18:37                     ` Linus Torvalds
2020-12-10 18:38                     ` Davidlohr Bueso
2020-12-10 19:40                       ` Eric W. Biederman
2020-12-05 17:43           ` [PATCH 3/3] exec: Transform exec_update_mutex into a rw_semaphore Eric W. Biederman
2020-12-04 17:39     ` Eric W. Biederman
2020-12-03 22:42 ` [PATCH 0/3] " Linus Torvalds
2020-12-04  1:56   ` Waiman Long
2020-12-04  4:54   ` Davidlohr Bueso

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