linux-kernel - Re: [PATCH v2 3/3] firmware: Avoid bogus fallback warning

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Date:	Tue, 12 Nov 2013 07:26:08 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Prarit Bhargava <prarit@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org, amd64-microcode <amd64-microcode@...64.org>
Subject: Re: [PATCH v2 3/3] firmware: Avoid bogus fallback warning

At Tue, 12 Nov 2013 09:40:24 +0800,
Ming Lei wrote:
At Tue, 12 Nov 2013 09:40:24 +0800,
Ming Lei wrote:
> 
> On Mon, Nov 11, 2013 at 11:21 PM, Takashi Iwai <tiwai@...e.de> wrote:
> > The commit [3e358ac2bb5b: firmware: Be a bit more verbose about direct
> > firmware loading failure] introduced a new warning message about
> > falling back to user helper, but this isn't true when
> > CONFIG_FW_LOADER_USER_HELPER isn't set.
> >
> > For avoiding the confusion, add a proper ifdef.  And now we can remove
> > the dummy fw_load_from_user_helper(), too, since it's no longer called
> > with CONFIG_FW_LOADER_USER_HELPER=n.
> >
> > Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > ---
> >  drivers/base/firmware_class.c | 10 ++--------
> >  1 file changed, 2 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> > index 7f48a6ffb0df..bb03c71bd94d 100644
> > --- a/drivers/base/firmware_class.c
> > +++ b/drivers/base/firmware_class.c
> > @@ -940,14 +940,6 @@ static void kill_requests_without_uevent(void)
> >  #endif
> >
> >  #else /* CONFIG_FW_LOADER_USER_HELPER */
> > -static inline int
> > -fw_load_from_user_helper(struct firmware *firmware, const char *name,
> > -                        struct device *device, bool uevent, bool nowait,
> > -                        long timeout)
> > -{
> > -       return -ENOENT;
> > -}
> > -
> >  /* No abort during direct loading */
> >  #define is_fw_load_aborted(buf) false
> >
> > @@ -1097,11 +1089,13 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
> >         if (ret) {
> >                 dev_warn(device, "Direct firmware load failed with error %d\n",
> >                          ret);
> > +#ifdef CONFIG_FW_LOADER_USER_HELPER
> >                 if (fallback) {
> >                         dev_warn(device, "Falling back to user helper\n");
> 
> I think it is simpler to put above line at the entry of
> fw_load_from_user_helper()
> since we always do direct-loading first, and code should be cleaner.
> 
> Thanks,
> --
> Ming Lei
> 
> 
> On Mon, Nov 11, 2013 at 11:21 PM, Takashi Iwai <tiwai@...e.de> wrote:
> > The commit [3e358ac2bb5b: firmware: Be a bit more verbose about direct
> > firmware loading failure] introduced a new warning message about
> > falling back to user helper, but this isn't true when
> > CONFIG_FW_LOADER_USER_HELPER isn't set.
> >
> > For avoiding the confusion, add a proper ifdef.  And now we can remove
> > the dummy fw_load_from_user_helper(), too, since it's no longer called
> > with CONFIG_FW_LOADER_USER_HELPER=n.
> >
> > Signed-off-by: Takashi Iwai <tiwai@...e.de>
> > ---
> >  drivers/base/firmware_class.c | 10 ++--------
> >  1 file changed, 2 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> > index 7f48a6ffb0df..bb03c71bd94d 100644
> > --- a/drivers/base/firmware_class.c
> > +++ b/drivers/base/firmware_class.c
> > @@ -940,14 +940,6 @@ static void kill_requests_without_uevent(void)
> >  #endif
> >
> >  #else /* CONFIG_FW_LOADER_USER_HELPER */
> > -static inline int
> > -fw_load_from_user_helper(struct firmware *firmware, const char *name,
> > -                        struct device *device, bool uevent, bool nowait,
> > -                        long timeout)
> > -{
> > -       return -ENOENT;
> > -}
> > -
> >  /* No abort during direct loading */
> >  #define is_fw_load_aborted(buf) false
> >
> > @@ -1097,11 +1089,13 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
> >         if (ret) {
> >                 dev_warn(device, "Direct firmware load failed with error %d\n",
> >                          ret);
> > +#ifdef CONFIG_FW_LOADER_USER_HELPER
> >                 if (fallback) {
> >                         dev_warn(device, "Falling back to user helper\n");
> 
> I think it is simpler to put above line at the entry of
> fw_load_from_user_helper()
> since we always do direct-loading first, and code should be cleaner.

OK, that makes sense.

While looking back at the code, I think the first warning ("Direct
firmware load failed" should be suppressed, too, when no fallback is
set.  For example, non-existing firmware is no error at all for
microcode driver, as a firmware is purely optional.  Showing a warning
at each failure would result in lots of bogus warnings and it'd
confuse users as if something critical happened.

So, the first dev_warn() is better in the "if (fallback)" block, IMO.

I'm going to prepare the v3 patch series together with bit flags
change.


thanks,

Takashi
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