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Message-ID: <CADAEsF89WyoBA2vEadOUL6qeEQtGGMm5XFNpXRJh7FpZpJUneQ@mail.gmail.com> Date: Mon, 2 Apr 2018 09:33:30 +0800 From: Ganesh Mahendran <opensource.ganesh@...il.com> To: Geert Uytterhoeven <geert@...ux-m68k.org> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>, Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>, "Rafael J. Wysocki" <rafael@...nel.org>, Greg KH <gregkh@...uxfoundation.org>, Linux PM list <linux-pm@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v2] PM / wakeup: use seq_open() to show wakeup stats 2018-03-30 19:00 GMT+08:00 Geert Uytterhoeven <geert@...ux-m68k.org>: > On Fri, Mar 30, 2018 at 12:25 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote: >> On Monday, March 5, 2018 9:47:46 AM CEST Ganesh Mahendran wrote: >>> single_open() interface requires that the whole output must >>> fit into a single buffer. This will lead to timeout when >>> system memory is not in a good situation. >>> >>> This patch use seq_open() to show wakeup stats. This method >>> need only one page, so timeout will not be observed. >>> >>> Signed-off-by: Ganesh Mahendran <opensource.ganesh@...il.com> >>> ---- >>> v2: use srcu_read_lock instead of rcu_read_lock >>> --- >>> drivers/base/power/wakeup.c | 77 +++++++++++++++++++++++++++++++++++---------- >>> 1 file changed, 61 insertions(+), 16 deletions(-) >>> >>> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c >>> index ea01621..3bcab7d 100644 >>> --- a/drivers/base/power/wakeup.c >>> +++ b/drivers/base/power/wakeup.c >>> @@ -1029,32 +1029,77 @@ static int print_wakeup_source_stats(struct seq_file *m, >>> return 0; >>> } >>> >>> -/** >>> - * wakeup_sources_stats_show - Print wakeup sources statistics information. >>> - * @m: seq_file to print the statistics into. >>> - */ >>> -static int wakeup_sources_stats_show(struct seq_file *m, void *unused) >>> +static void *wakeup_sources_stats_seq_start(struct seq_file *m, >>> + loff_t *pos) >>> { >>> struct wakeup_source *ws; >>> - int srcuidx; >>> + loff_t n = *pos; >>> + int *srcuidx = m->private; >>> >>> - seq_puts(m, "name\t\tactive_count\tevent_count\twakeup_count\t" >>> - "expire_count\tactive_since\ttotal_time\tmax_time\t" >>> - "last_change\tprevent_suspend_time\n"); >>> + if (n == 0) { >>> + seq_puts(m, "name\t\tactive_count\tevent_count\twakeup_count\t" >>> + "expire_count\tactive_since\ttotal_time\tmax_time\t" >>> + "last_change\tprevent_suspend_time\n"); >>> + } >>> >>> - srcuidx = srcu_read_lock(&wakeup_srcu); >>> - list_for_each_entry_rcu(ws, &wakeup_sources, entry) >>> - print_wakeup_source_stats(m, ws); >>> - srcu_read_unlock(&wakeup_srcu, srcuidx); >>> + *srcuidx = srcu_read_lock(&wakeup_srcu); >>> + list_for_each_entry_rcu(ws, &wakeup_sources, entry) { >>> + if (n-- > 0) >>> + continue; >>> + goto out; >>> + } >>> + ws = NULL; >>> +out: >>> + return ws; >>> +} >> >> Please clean up the above at least. >> >> If I'm not mistaken, you don't need the label and the goto here. > > The continue is also not needed, if the test condition is inverted. Hi, Geert We need to locate to the last read item. What is your suggestion here? Thanks. > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds
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