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Date: Wed, 2 Aug 2017 23:30:10 +0200
From: "Luis R. Rodriguez" <mcgrof@...nel.org>
To: Rafał Miłecki <zajec5@...il.com>
Cc: "Luis R . Rodriguez" <mcgrof@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Daniel Wagner <wagi@...om.org>,
David Woodhouse <dwmw2@...radead.org>,
Arend van Spriel <arend.vanspriel@...adcom.com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>, yi1.li@...ux.intel.com,
atull@...nel.org, Moritz Fischer <moritz.fischer@...us.com>,
pmladek@...e.com, Johannes Berg <johannes.berg@...el.com>,
emmanuel.grumbach@...el.com, luciano.coelho@...el.com,
Kalle Valo <kvalo@...eaurora.org>, luto@...nel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Kees Cook <keescook@...omium.org>,
AKASHI Takahiro <takahiro.akashi@...aro.org>,
David Howells <dhowells@...hat.com>, pjones@...hat.com,
Hans de Goede <hdegoede@...hat.com>, alan@...ux.intel.com,
tytso@....edu, lkml <linux-kernel@...r.kernel.org>,
Franky Lin <franky.lin@...adcom.com>,
Hante Meuleman <hante.meuleman@...adcom.com>,
Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
Wright Feng <wright.feng@...ress.com>,
Pieter-Paul Giesberts <pieter-paul.giesberts@...adcom.com>,
linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH V5 1/2] firmware: add more flexible
request_firmware_async function
On Mon, Jul 31, 2017 at 05:09:44PM +0200, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@...ecki.pl>
>
> So far we got only one function for loading firmware asynchronously:
> request_firmware_nowait. It didn't allow much customization of firmware
> loading process - there is only one bool uevent argument. Moreover this
> bool also controls user helper in an unclear way.
> Some drivers need more flexible helper providing more options. This
> includes control over uevent or warning for the missing firmware. Of
> course this list may grow up in the future.
>
> To handle this easily this patch adds a generic request_firmware_async
> function. It takes struct with options as an argument which will allow
> extending it in the future without massive changes.
>
> This is a really cheap change (no new independent API) which works
> nicely with the existing code. The old request_firmware_nowait is kept
> as a simple helper calling new helper.
>
> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
> ---
> V3: Don't expose all FW_OPT_* flags.
> As Luis noted we want a struct so add struct firmware_opts for real
> flexibility.
> Thank you Luis for your review!
> V5: Rebase, update commit message, resend after drvdata discussion
> ---
> drivers/base/firmware_class.c | 43 ++++++++++++++++++++++++++++++++++---------
> include/linux/firmware.h | 15 ++++++++++++++-
> 2 files changed, 48 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index b9f907eedbf7..cde85b05e4cb 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -1375,7 +1375,7 @@ static void request_firmware_work_func(struct work_struct *work)
> _request_firmware(&fw, fw_work->name, fw_work->device, NULL, 0,
> fw_work->opt_flags);
> fw_work->cont(fw, fw_work->context);
> - put_device(fw_work->device); /* taken in request_firmware_nowait() */
> + put_device(fw_work->device); /* taken in __request_firmware_nowait() */
>
> module_put(fw_work->module);
> kfree_const(fw_work->name);
> @@ -1383,10 +1383,9 @@ static void request_firmware_work_func(struct work_struct *work)
> }
>
> /**
> - * request_firmware_nowait - asynchronous version of request_firmware
> + * __request_firmware_nowait - asynchronous version of request_firmware
> * @module: module requesting the firmware
> - * @uevent: sends uevent to copy the firmware image if this flag
> - * is non-zero else the firmware copy must be done manually.
> + * @opt_flags: flags that control firmware loading process, see FW_OPT_*
> * @name: name of firmware file
> * @device: device for which firmware is being loaded
> * @gfp: allocation flags
> @@ -1405,9 +1404,9 @@ static void request_firmware_work_func(struct work_struct *work)
> *
> * - can't sleep at all if @gfp is GFP_ATOMIC.
> **/
> -int
> -request_firmware_nowait(
> - struct module *module, bool uevent,
> +static int
> +__request_firmware_nowait(
> + struct module *module, unsigned int opt_flags,
> const char *name, struct device *device, gfp_t gfp, void *context,
> void (*cont)(const struct firmware *fw, void *context))
> {
> @@ -1426,8 +1425,7 @@ request_firmware_nowait(
> fw_work->device = device;
> fw_work->context = context;
> fw_work->cont = cont;
> - fw_work->opt_flags = FW_OPT_NOWAIT | FW_OPT_FALLBACK |
> - (uevent ? FW_OPT_UEVENT : FW_OPT_USERHELPER);
> + fw_work->opt_flags = FW_OPT_NOWAIT | opt_flags;
>
> if (!try_module_get(module)) {
> kfree_const(fw_work->name);
> @@ -1440,8 +1438,35 @@ request_firmware_nowait(
> schedule_work(&fw_work->work);
> return 0;
> }
> +
> +int request_firmware_nowait(struct module *module, bool uevent,
> + const char *name, struct device *device, gfp_t gfp,
> + void *context,
> + void (*cont)(const struct firmware *fw, void *context))
> +{
> + unsigned int opt_flags = FW_OPT_FALLBACK |
> + (uevent ? FW_OPT_UEVENT : FW_OPT_USERHELPER);
> +
> + return __request_firmware_nowait(module, opt_flags, name, device, gfp,
> + context, cont);
> +}
> EXPORT_SYMBOL(request_firmware_nowait);
>
> +int __request_firmware_async(struct module *module, const char *name,
> + struct firmware_opts *fw_opts, struct device *dev,
> + void *context,
> + void (*cont)(const struct firmware *fw, void *context))
> +{
> + unsigned int opt_flags = FW_OPT_UEVENT;
This exposes a long issue. Think -- why do we want this enabled by default? Its
actually because even though the fallback stuff is optional and can be, the uevent
internal flag *also* provides caching support as a side consequence only. We
don't want to add a new API without first cleaning up that mess.
This is a slipery slope and best to clean that up before adding any new API.
That and also Greg recently stated he would like to see at least 3 users of
a feature before adding it. Although I think that's pretty arbitrary, and
considering that request_firmware_into_buf() only has *one* user -- its what
he wishes.
Luis
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