From: Peter Zijlstra Subject: Re: [PATCH 01/42] percpu counter: clean up percpu_counter_sum_and_set() Date: Thu, 09 Oct 2008 10:52:52 +0200 Message-ID: <1223542372.7382.30.camel@lappy.programming.kicks-ass.net> References: <1223525160-9887-1-git-send-email-tytso@mit.edu> <1223525160-9887-2-git-send-email-tytso@mit.edu> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Mingming Cao , Andrew Morton To: Theodore Ts'o Return-path: Received: from casper.infradead.org ([85.118.1.10]:34215 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752754AbYJIIyR (ORCPT ); Thu, 9 Oct 2008 04:54:17 -0400 In-Reply-To: <1223525160-9887-2-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, 2008-10-09 at 00:05 -0400, Theodore Ts'o wrote: > From: Mingming Cao > > percpu_counter_sum_and_set() and percpu_counter_sum() is the same except > the former updates the global counter after accounting. Since we are > taking the fbc->lock to calculate the precise value of the counter in > percpu_counter_sum() anyway, it should simply set fbc->count too, as the > percpu_counter_sum_and_set() does. > > This patch merge these two interfaces into one. I totally missed the patch introducing this _and_set() horror, but this does look like a good cleanup. Thanks Mingming! Acked-by: Peter Zijlstra > Signed-off-by: Mingming Cao > Cc: Peter Zijlstra > Cc: > Signed-off-by: Andrew Morton > Signed-off-by: "Theodore Ts'o" > --- > fs/ext4/balloc.c | 2 +- > include/linux/percpu_counter.h | 12 +++--------- > lib/percpu_counter.c | 8 +++----- > 3 files changed, 7 insertions(+), 15 deletions(-) > > diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c > index e9fa960..00a94d5 100644 > --- a/fs/ext4/balloc.c > +++ b/fs/ext4/balloc.c > @@ -1624,7 +1624,7 @@ ext4_fsblk_t ext4_has_free_blocks(struct ext4_sb_info *sbi, > #ifdef CONFIG_SMP > if (free_blocks - root_blocks < FBC_BATCH) > free_blocks = > - percpu_counter_sum_and_set(&sbi->s_freeblocks_counter); > + percpu_counter_sum(&sbi->s_freeblocks_counter); > #endif > if (free_blocks <= root_blocks) > /* we don't have free space */ > diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h > index 2083888..9007ccd 100644 > --- a/include/linux/percpu_counter.h > +++ b/include/linux/percpu_counter.h > @@ -35,7 +35,7 @@ int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount); > void percpu_counter_destroy(struct percpu_counter *fbc); > void percpu_counter_set(struct percpu_counter *fbc, s64 amount); > void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch); > -s64 __percpu_counter_sum(struct percpu_counter *fbc, int set); > +s64 __percpu_counter_sum(struct percpu_counter *fbc); > > static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount) > { > @@ -44,19 +44,13 @@ static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount) > > static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc) > { > - s64 ret = __percpu_counter_sum(fbc, 0); > + s64 ret = __percpu_counter_sum(fbc); > return ret < 0 ? 0 : ret; > } > > -static inline s64 percpu_counter_sum_and_set(struct percpu_counter *fbc) > -{ > - return __percpu_counter_sum(fbc, 1); > -} > - > - > static inline s64 percpu_counter_sum(struct percpu_counter *fbc) > { > - return __percpu_counter_sum(fbc, 0); > + return __percpu_counter_sum(fbc); > } > > static inline s64 percpu_counter_read(struct percpu_counter *fbc) > diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c > index 4a8ba4b..a866389 100644 > --- a/lib/percpu_counter.c > +++ b/lib/percpu_counter.c > @@ -52,7 +52,7 @@ EXPORT_SYMBOL(__percpu_counter_add); > * Add up all the per-cpu counts, return the result. This is a more accurate > * but much slower version of percpu_counter_read_positive() > */ > -s64 __percpu_counter_sum(struct percpu_counter *fbc, int set) > +s64 __percpu_counter_sum(struct percpu_counter *fbc) > { > s64 ret; > int cpu; > @@ -62,11 +62,9 @@ s64 __percpu_counter_sum(struct percpu_counter *fbc, int set) > for_each_online_cpu(cpu) { > s32 *pcount = per_cpu_ptr(fbc->counters, cpu); > ret += *pcount; > - if (set) > - *pcount = 0; > + *pcount = 0; > } > - if (set) > - fbc->count = ret; > + fbc->count = ret; > > spin_unlock(&fbc->lock); > return ret;