linux-kernel - [PATCH] mutex: nuke mutex_trylock

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Date:   Tue, 16 Feb 2021 09:21:46 +0100
From:   "Christian König" 
        <ckoenig.leichtzumerken@...il.com>
To:     peterz@...radead.org, mingo@...hat.com, will@...nel.org,
        apw@...onical.com, joe@...ches.com, linux-kernel@...r.kernel.org
Cc:     dri-devel@...ts.freedesktop.org
Subject: [PATCH] mutex: nuke mutex_trylock_recursive

The last user went away in the 5.11 cycle.

Signed-off-by: Christian König <christian.koenig@....com>
---
 include/linux/mutex.h  | 25 -------------------------
 kernel/locking/mutex.c | 10 ----------
 scripts/checkpatch.pl  |  6 ------
 3 files changed, 41 deletions(-)

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index dcd185cbfe79..0cd631a19727 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -199,29 +199,4 @@ extern void mutex_unlock(struct mutex *lock);
 
 extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
 
-/*
- * These values are chosen such that FAIL and SUCCESS match the
- * values of the regular mutex_trylock().
- */
-enum mutex_trylock_recursive_enum {
-	MUTEX_TRYLOCK_FAILED    = 0,
-	MUTEX_TRYLOCK_SUCCESS   = 1,
-	MUTEX_TRYLOCK_RECURSIVE,
-};
-
-/**
- * mutex_trylock_recursive - trylock variant that allows recursive locking
- * @lock: mutex to be locked
- *
- * This function should not be used, _ever_. It is purely for hysterical GEM
- * raisins, and once those are gone this will be removed.
- *
- * Returns:
- *  - MUTEX_TRYLOCK_FAILED    - trylock failed,
- *  - MUTEX_TRYLOCK_SUCCESS   - lock acquired,
- *  - MUTEX_TRYLOCK_RECURSIVE - we already owned the lock.
- */
-extern /* __deprecated */ __must_check enum mutex_trylock_recursive_enum
-mutex_trylock_recursive(struct mutex *lock);
-
 #endif /* __LINUX_MUTEX_H */
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 5352ce50a97e..adb935090768 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -86,16 +86,6 @@ bool mutex_is_locked(struct mutex *lock)
 }
 EXPORT_SYMBOL(mutex_is_locked);
 
-__must_check enum mutex_trylock_recursive_enum
-mutex_trylock_recursive(struct mutex *lock)
-{
-	if (unlikely(__mutex_owner(lock) == current))
-		return MUTEX_TRYLOCK_RECURSIVE;
-
-	return mutex_trylock(lock);
-}
-EXPORT_SYMBOL(mutex_trylock_recursive);
-
 static inline unsigned long __owner_flags(unsigned long owner)
 {
 	return owner & MUTEX_FLAGS;
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 92e888ed939f..15f7f4fa6b99 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -7069,12 +7069,6 @@ sub process {
 			}
 		}
 
-# check for mutex_trylock_recursive usage
-		if ($line =~ /mutex_trylock_recursive/) {
-			ERROR("LOCKING",
-			      "recursive locking is bad, do not use this ever.\n" . $herecurr);
-		}
-
 # check for lockdep_set_novalidate_class
 		if ($line =~ /^.\s*lockdep_set_novalidate_class\s*\(/ ||
 		    $line =~ /__lockdep_no_validate__\s*\)/ ) {
-- 
2.25.1