From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH v5 6/7] locking/lockdep: Reuse freed chain_hlocks entries
Date: Tue, 4 Feb 2020 16:42:36 +0100 [thread overview]
Message-ID: <20200204154236.GE14879@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200203164147.17990-7-longman@redhat.com>
On Mon, Feb 03, 2020 at 11:41:46AM -0500, Waiman Long wrote:
> + /*
> + * We require a minimum of 2 (u16) entries to encode a freelist
> + * 'pointer'.
> + */
> + req = max(req, 2);
Would something simple like the below not avoid that whole 1 entry
'chain' nonsense?
It boots and passes the selftests, so it must be perfect :-)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3163,7 +3163,7 @@ static int validate_chain(struct task_st
* (If lookup_chain_cache_add() return with 1 it acquires
* graph_lock for us)
*/
- if (!hlock->trylock && hlock->check &&
+ if (!chain_head && !hlock->trylock && hlock->check &&
lookup_chain_cache_add(curr, hlock, chain_key)) {
/*
* Check whether last held lock:
next prev parent reply other threads:[~2020-02-04 15:42 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-03 16:41 [PATCH v5 0/7] locking/lockdep: Reuse zapped " Waiman Long
2020-02-03 16:41 ` [PATCH v5 1/7] locking/lockdep: Decrement irq context counters when removing lock chain Waiman Long
2020-02-03 16:41 ` [PATCH v5 2/7] locking/lockdep: Display irq_context names in /proc/lockdep_chains Waiman Long
2020-02-03 16:41 ` [PATCH v5 3/7] locking/lockdep: Track number of zapped classes Waiman Long
2020-02-03 16:41 ` [PATCH v5 4/7] locking/lockdep: Throw away all lock chains with zapped class Waiman Long
2020-02-03 16:41 ` [PATCH v5 5/7] locking/lockdep: Track number of zapped lock chains Waiman Long
2020-02-03 16:41 ` [PATCH v5 6/7] locking/lockdep: Reuse freed chain_hlocks entries Waiman Long
2020-02-04 12:36 ` Peter Zijlstra
2020-02-04 14:54 ` Waiman Long
2020-02-04 16:45 ` Waiman Long
2020-02-05 9:41 ` Peter Zijlstra
2020-02-05 13:59 ` Waiman Long
2020-02-04 15:42 ` Peter Zijlstra [this message]
2020-02-04 16:12 ` Waiman Long
2020-02-04 16:26 ` Waiman Long
2020-02-04 16:57 ` Waiman Long
2020-02-05 9:48 ` Peter Zijlstra
2020-02-05 14:03 ` Waiman Long
2020-02-03 16:41 ` [PATCH v5 7/7] locking/lockdep: Add a fast path for chain_hlocks allocation Waiman Long
2020-02-04 12:47 ` Peter Zijlstra
2020-02-04 15:07 ` Waiman Long
2020-02-04 13:18 ` Peter Zijlstra
2020-02-04 13:44 ` Peter Zijlstra
2020-02-04 18:02 ` Waiman Long
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