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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Mauro Carvalho Chehab <mchehab@s-opensource.com>,
	"David S . Miller" <davem@davemloft.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Pavan Kondeti <pkondeti@codeaurora.org>,
	Ingo Molnar <mingo@kernel.org>,
	Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH 01/32] locking/lockdep: Use expanded masks on find_usage_*() functions
Date: Tue, 12 Feb 2019 09:35:34 -0800	[thread overview]
Message-ID: <CAHk-=wjYBy=TBCLwoh4v_7nf4kqLrt1h6D4CsVM7Ws2e06Efcg@mail.gmail.com> (raw)
In-Reply-To: <20190212171423.8308-2-frederic@kernel.org>

On Tue, Feb 12, 2019 at 9:14 AM Frederic Weisbecker <frederic@kernel.org> wrote:
>
> In order to perform softirq vector-finegrained locking validation we'll
> need to be able to check multiple vector usages at once. Prepare the low
> level usage mask check functions for that purpose.

Why is this using "u64 mask"?

That's not only fairly expensive on 32-bit targets, it wasn't what the
code did before:

> -static inline int usage_match(struct lock_list *entry, void *bit)
> +static inline int usage_match(struct lock_list *entry, void *mask)
>  {
> -       return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
> +       return entry->class->usage_mask & *(u64 *)mask;

Note how that was an "int" mask value before, and "usage_mask" itself
is just "unsigned long".

So where does that "u64" come from?

If there is some reason you really want to use a 64-bit value (some
future change?), it should be documented.

                Linus

  reply	other threads:[~2019-02-12 17:36 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-12 17:13 [PATCH 00/32] softirq: Per vector masking v2 Frederic Weisbecker
2019-02-12 17:13 ` [PATCH 01/32] locking/lockdep: Use expanded masks on find_usage_*() functions Frederic Weisbecker
2019-02-12 17:35   ` Linus Torvalds [this message]
2019-02-12 17:13 ` [PATCH 02/32] locking/lockdep: Introduce struct lock_usage Frederic Weisbecker
2019-02-12 17:38   ` Linus Torvalds
2019-02-13 14:56     ` Frederic Weisbecker
2019-02-12 17:13 ` [PATCH 03/32] locking/lockdep: Convert usage_mask to u64 Frederic Weisbecker
2019-02-12 17:40   ` Linus Torvalds
2019-02-13 14:51     ` Frederic Weisbecker
2019-02-12 17:13 ` [PATCH 04/32] locking/lockdep: Test all incompatible scenario at once in check_irq_usage() Frederic Weisbecker
2019-02-12 17:13 ` [PATCH 05/32] locking/lockdep: Prepare valid_state() to handle plain masks Frederic Weisbecker
2019-02-12 17:45   ` Linus Torvalds
2019-02-13 15:16     ` Frederic Weisbecker
2019-02-13 19:47       ` Linus Torvalds
2019-02-21  3:53         ` Frederic Weisbecker
2019-02-12 17:13 ` [PATCH 06/32] locking/lockdep: Prepare check_usage_*() " Frederic Weisbecker
2019-02-12 17:13 ` [PATCH 07/32] locking/lockdep: Prepare state_verbose() to handle all softirqs Frederic Weisbecker
2019-02-12 17:13 ` [PATCH 08/32] locking/lockdep: Make mark_lock() fastpath to work with multiple usage at once Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 09/32] locking/lockdep: Save stack trace for each softirq vector involved Frederic Weisbecker
2019-02-12 17:47   ` Linus Torvalds
2019-02-13 15:18     ` Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 10/32] locking/lockdep: Make mark_lock() verbosity aware of vector Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 11/32] softirq: Macrofy softirq vectors Frederic Weisbecker
2019-02-27  9:54   ` Sebastian Andrzej Siewior
2019-02-27 23:08     ` Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 12/32] locking/lockdep: Define per vector softirq lock usage states Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 13/32] softirq: Pass softirq vector number to lockdep on vector execution Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 14/32] x86: Revert "x86/irq: Demote irq_cpustat_t::__softirq_pending to u16" Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 15/32] arch/softirq: Rename softirq_pending fields to softirq_data Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 16/32] softirq: Normalize softirq_pending naming scheme Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 17/32] softirq: Convert softirq_pending_*() to set/clear mask scheme Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 18/32] softirq: Introduce disabled softirq vectors bits Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 19/32] softirq: Rename _local_bh_enable() to local_bh_enable_no_softirq() Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 20/32] softirq: Move vectors bits to bottom_half.h Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 21/32] x86: Init softirq enabled field Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 22/32] softirq: Check enabled vectors before processing Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 23/32] softirq: Remove stale comment Frederic Weisbecker
2019-02-27 11:04   ` Sebastian Andrzej Siewior
2019-02-27 23:09     ` Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 24/32] softirq: Uninline !CONFIG_TRACE_IRQFLAGS __local_bh_disable_ip() Frederic Weisbecker
2019-02-27 11:14   ` Sebastian Andrzej Siewior
2019-02-27 23:14     ` Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 25/32] softirq: Prepare for mixing all/per-vector masking Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 26/32] softirq: Support per vector masking Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 27/32] locking/lockdep: Remove redundant softirqs on check Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 28/32] locking/lockdep: Update check_flags() according to new layout Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 29/32] locking/lockdep: Branch the new vec-finegrained softirq masking to lockdep Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 30/32] softirq: Allow to soft interrupt vector-specific masked contexts Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 31/32] locking: Introduce spin_[un]lock_bh_mask() Frederic Weisbecker
2019-02-12 17:14 ` [PATCH 32/32] net: Make softirq vector masking finegrained on release_sock() Frederic Weisbecker
2019-02-12 18:29 ` [PATCH 00/32] softirq: Per vector masking v2 David Miller

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