Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932561Ab3CLK1g (ORCPT ); Tue, 12 Mar 2013 06:27:36 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:44192 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932115Ab3CLK1e (ORCPT ); Tue, 12 Mar 2013 06:27:34 -0400 Message-ID: <1363084030.14933.23.camel@laptop> Subject: Re: [PATCHv3] perf: Fix vmalloc ring buffer free function From: Peter Zijlstra To: Jiri Olsa Cc: linux-kernel@vger.kernel.org, Corey Ashford , Frederic Weisbecker , Ingo Molnar , Namhyung Kim , Paul Mackerras , Arnaldo Carvalho de Melo Date: Tue, 12 Mar 2013 11:27:10 +0100 In-Reply-To: <20130312100502.GC1348@krava.brq.redhat.com> References: <1362155689-13719-1-git-send-email-jolsa@redhat.com> <1362994843.10972.40.camel@laptop> <20130311112105.GA9737@krava.brq.redhat.com> <1363019193.14933.14.camel@laptop> <20130311164309.GG13679@krava.brq.redhat.com> <1363023885.14933.16.camel@laptop> <20130311180229.GI13679@krava.brq.redhat.com> <20130312100502.GC1348@krava.brq.redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2430 Lines: 74 On Tue, 2013-03-12 at 11:05 +0100, Jiri Olsa wrote: > +/* > + * Returns the total number of pages allocated > + * by ring buffer including the user page. > + */ > +static int page_nr(struct ring_buffer *rb) > +{ > + return page_order(rb) == -1 ? > + 1 : /* no data, just user page */ > + 1 + (1 << page_order(rb)); /* user page + data pages */ > +} > @@ -371,9 +381,24 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) > goto fail_all_buf; > > rb->user_page = all_buf; > - rb->data_pages[0] = all_buf + PAGE_SIZE; > - rb->page_order = ilog2(nr_pages); > - rb->nr_pages = 1; > + > + rb->data_pages[0] = nr_pages ? all_buf + PAGE_SIZE : NULL; > + rb->nr_pages = nr_pages ? 1 : 0; > + rb->page_order = ilog2(nr_pages); > > ring_buffer_init(rb, watermark, flags); Still somewhat confused by this.. wouldn't something 'simple' like the below suffice? Note how the !vmalloc branch also sets rb->nr_pages = nr_pages. --- kernel/events/ring_buffer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 23cb34f..4f48d02 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -316,7 +316,7 @@ void rb_free(struct ring_buffer *rb) struct page * perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff) { - if (pgoff > (1UL << page_order(rb))) + if (pgoff > rb->nr_pages) return NULL; return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE); @@ -336,7 +336,7 @@ static void rb_free_work(struct work_struct *work) int i, nr; rb = container_of(work, struct ring_buffer, work); - nr = 1 << page_order(rb); + nr = rb->nr_pages; base = rb->user_page; for (i = 0; i < nr + 1; i++) @@ -373,7 +373,7 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) rb->user_page = all_buf; rb->data_pages[0] = all_buf + PAGE_SIZE; rb->page_order = ilog2(nr_pages); - rb->nr_pages = 1; + rb->nr_pages = nr_pages; ring_buffer_init(rb, watermark, flags); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/