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    SubjectRe: [PATCH v4 01/21] genirq/devres: Add devm_request_threaded_irq_probe() and devm_request_irq_probe()
    On Mon, 10 Jul 2023 14:25:24 +0200
    Geert Uytterhoeven <geert@linux-m68k.org> wrote:

    > Hi Yangtao,
    >
    > On Mon, Jul 10, 2023 at 12:05 PM Yangtao Li <frank.li@vivo.com> wrote:
    > > There are more than 700 calls to devm_request_threaded_irq method and
    > > more than 1000 calls to devm_request_irq method. Most drivers only
    > > request one interrupt resource, and these error messages are basically
    > > the same. If error messages are printed everywhere, more than 2000 lines
    > > of code can be saved by removing the msg in the driver.
    > >
    > > And tglx point out that:
    > >
    > > If we actually look at the call sites of
    > > devm_request_threaded_irq() then the vast majority of them print more or
    > > less lousy error messages. A quick grep/sed/awk/sort/uniq revealed
    > >
    > > 519 messages total (there are probably more)
    > >
    > > 352 unique messages
    > >
    > > 323 unique messages after lower casing
    > >
    > > Those 323 are mostly just variants of the same patterns with
    > > slight modifications in formatting and information provided.
    > >
    > > 186 of these messages do not deliver any useful information,
    > > e.g. "no irq", "
    > >
    > > The most useful one of all is: "could request wakeup irq: %d"
    > >
    > > So there is certainly an argument to be made that this particular
    > > function should print a well formatted and informative error message.
    > >
    > > It's not a general allocator like kmalloc(). It's specialized and in the
    > > vast majority of cases failing to request the interrupt causes the
    > > device probe to fail. So having proper and consistent information why
    > > the device cannot be used _is_ useful.
    > >
    > > So add devm_request_threaded_irq_probe() and devm_request_irq_probe(),
    > > which ensure that all error handling branches print error information.
    > > In this way, when this function fails, the upper-layer functions can
    > > directly return an error code without missing debugging information.
    > > Otherwise, the error message will be printed redundantly or missing.
    > >
    > > Cc: Thomas Gleixner <tglx@linutronix.de>
    > > Cc: Krzysztof Kozlowski <krzk@kernel.org>
    > > Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
    > > Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
    > > Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
    > > Signed-off-by: Yangtao Li <frank.li@vivo.com>
    >
    > Thanks for your patch!
    >
    > > --- a/include/linux/interrupt.h
    > > +++ b/include/linux/interrupt.h
    > > @@ -201,6 +201,21 @@ extern void free_percpu_nmi(unsigned int irq, void __percpu *percpu_dev_id);
    > >
    > > struct device;
    > >
    > > +extern int __must_check
    > > +devm_request_threaded_irq_probe(struct device *dev, unsigned int irq,
    > > + irq_handler_t handler, irq_handler_t thread_fn,
    > > + unsigned long irqflags, const char *devname,
    > > + void *dev_id, const char *info);
    > > +
    > > +static inline int __must_check
    > > +devm_request_irq_probe(struct device *dev, unsigned int irq,
    > > + irq_handler_t handler, unsigned long irqflags,
    > > + const char *devname, void *dev_id, const char *info)
    > > +{
    > > + return devm_request_threaded_irq_probe(dev, irq, handler, NULL, irqflags,
    > > + devname, dev_id, info);
    > > +}
    > > +
    > > extern int __must_check
    > > devm_request_threaded_irq(struct device *dev, unsigned int irq,
    > > irq_handler_t handler, irq_handler_t thread_fn,
    > > diff --git a/kernel/irq/devres.c b/kernel/irq/devres.c
    > > index f6e5515ee077..43a40d6e2e0b 100644
    > > --- a/kernel/irq/devres.c
    > > +++ b/kernel/irq/devres.c
    > > @@ -79,6 +79,46 @@ int devm_request_threaded_irq(struct device *dev, unsigned int irq,
    > > }
    > > EXPORT_SYMBOL(devm_request_threaded_irq);
    > >
    > > +/**
    > > + * devm_request_threaded_irq_probe - allocate an interrupt line for a managed device
    It's awkward for the short description to be identical to devm_request_threaded_irq
    but I can't think of a sensible and short way to differentiate it.

    > > + * @dev: device to request interrupt for
    > > + * @irq: Interrupt line to allocate
    > > + * @handler: Function to be called when the IRQ occurs
    > > + * @thread_fn: function to be called in a threaded interrupt context. NULL
    > > + * for devices which handle everything in @handler
    > > + * @irqflags: Interrupt type flags
    > > + * @devname: An ascii name for the claiming device, dev_name(dev) if NULL
    > > + * @dev_id: A cookie passed back to the handler function
    > > + * @info: Optional additional error log
    > > + *
    > > + * This is a variant of the devm_request_threaded_irq function.
    > > + * It will print an error message by default when the request fails,
    > > + * and the consumer can add a special error msg.
    > > + *
    > > + * Except for the extra @dev argument, this function takes the
    >
    > ... extra @dev and @info arguments, ...
    >
    > > + * same arguments and performs the same function as
    > > + * request_threaded_irq(). IRQs requested with this function will be
    >
    > But probably you want to compare with devm_request_threaded_irq()
    > instead of with request_threaded_irq()?
    > I.e. "... extra @info argument..." above.
    >
    > > + * automatically freed on driver detach.
    > > + *
    > > + * If an IRQ allocated with this function needs to be freed
    > > + * separately, devm_free_irq() must be used.
    > > + */
    > > +int devm_request_threaded_irq_probe(struct device *dev, unsigned int irq,
    > > + irq_handler_t handler, irq_handler_t thread_fn,
    > > + unsigned long irqflags, const char *devname,
    > > + void *dev_id, const char *info)
    > > +{
    > > + int rc;
    > > +
    > > + rc = devm_request_threaded_irq(dev, irq, handler, NULL, irqflags, devname, dev_id);
    > > + if (rc)
    > > + return dev_err_probe(dev, rc, "Failed to request %sinterrupt %u %s %s\n",
    > > + thread_fn ? "threaded " : "", irq, devname ? : dev_name(dev),
    > > + info ? : "");
    > > + return 0;
    > > +}
    > > +EXPORT_SYMBOL(devm_request_threaded_irq_probe);
    > > +
    > > /**
    > > * devm_request_any_context_irq - allocate an interrupt line for a managed device
    > > * @dev: device to request interrupt for
    >
    > With the above fixed:
    > Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

    Likewise, lgtm
    Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

    I'd aim to get this upstream in one cycle with a few example drover changes
    but if you plan to do mass changes, leave them for the following cycle to
    make it really easy for maintainers to pick them up.

    Jonathan


    >
    > Gr{oetje,eeting}s,
    >
    > Geert
    >

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