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Message-ID: <20171218185657.GA6424@roeck-us.net>
Date: Mon, 18 Dec 2017 10:56:57 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Zoltan Boszormenyi <zboszor@...hu>
Cc: linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
linux-watchdog@...r.kernel.org, linux-i2c@...r.kernel.org,
Paul Menzel <paulepanter@...rs.sourceforge.net>,
Christian Fetzer <fetzer.ch@...il.com>,
Jean Delvare <jdelvare@...e.com>,
Nehal Shah <nehal-bakulchandra.shah@....com>,
Tim Small <tim@...ss.co.uk>, kernel@...ss.net, wim@...ana.be,
jlayton@...chiereds.net, marc.2377@...il.com,
cshorler@...glemail.com, wsa@...-dreams.de,
regressions@...mhuis.info,
Alex Williamson <alex.williamson@...hat.com>, lyude@...hat.com,
Linus Torvalds <torvalds@...ux-foundation.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Toshi Kani <toshi.kani@....com>,
Jiang Liu <jiang.liu@...ux.intel.com>,
Jakub Sitnicki <jsitnicki@...il.com>,
Thierry Reding <treding@...dia.com>,
Vivek Goyal <vgoyal@...hat.com>,
Ingo Molnar <mingo@...nel.org>,
Simon Guinot <simon.guinot@...uanux.org>,
Dan Williams <dan.j.williams@...el.com>,
Mike Travis <travis@....com>,
Daeseok Youn <daeseok.youn@...il.com>,
Huang Rui <ray.huang@....com>, Andiry Xu <andiry.xu@....com>,
Alan Cox <gnomes@...rguk.ukuu.org.uk>,
David Howells <dhowells@...hat.com>,
Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
Alexandre Desnoyers <alex@...c.com>,
Andy Shevchenko <andy.shevchenko@...il.com>,
Grygorii Strashko <grygorii.strashko@...com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Wan ZongShun <Vincent.Wan@....com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Lucas Stach <dev@...xeye.de>,
Denis Turischev <denis.turischev@...pulab.co.il>
Subject: Re: [PATCH 1/5 v3] Extend the request_region() infrastructure
On Mon, Dec 18, 2017 at 09:48:37AM +0100, Zoltan Boszormenyi wrote:
> From: Böszörményi Zoltán <zboszor@...hu>
>
> Add a new IORESOURCE_ALLOCATED flag that is automatically used
> when alloc_resource() is used internally in kernel/resource.c
> and free_resource() now takes this flag into account.
>
> The core of __request_region() was factored out into a new function
> called __request_declared_region() that needs struct resource *
> instead of the (start, n, name) triplet.
>
> These changes allow using statically declared struct resource
> data coupled with the pre-existing DEFINE_RES_IO_NAMED() static
> initializer macro. The new macro exploiting
> __request_declared_region() is request_declared_muxed_region()
>
> v2:
>
> Fixed checkpatch.pl warnings and errors and extended the macro
> API with request_declared_region() and release_declared_region()
>
> Reversed the order of __request_declared_region and __request_region
>
> Added high level description of the muxed and declared variants
> of the macros.
>
> v3:
>
> Rebased for 4.15-rc4
>
> Signed-off-by: Zoltán Böszörményi <zboszor@...hu>
> ---
> include/linux/ioport.h | 14 ++++++++++++++
> kernel/resource.c | 40 +++++++++++++++++++++++++++++++++++++---
> 2 files changed, 51 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 93b4183cf53d..d198d6a58574 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -53,6 +53,7 @@ struct resource {
> #define IORESOURCE_MEM_64 0x00100000
> #define IORESOURCE_WINDOW 0x00200000 /* forwarded by bridge */
> #define IORESOURCE_MUXED 0x00400000 /* Resource is software muxed */
> +#define IORESOURCE_ALLOCATED 0x00800000 /* Resource was allocated */
>
> #define IORESOURCE_EXT_TYPE_BITS 0x01000000 /* Resource extended types */
> #define IORESOURCE_SYSRAM 0x01000000 /* System RAM (modifier) */
> @@ -218,7 +219,14 @@ static inline bool resource_contains(struct resource *r1, struct resource *r2)
>
> /* Convenience shorthand with allocation */
> #define request_region(start,n,name) __request_region(&ioport_resource, (start), (n), (name), 0)
> +#define request_declared_region(res) __request_region( \
> + &ioport_resource, \
> + (res), 0)
> #define request_muxed_region(start,n,name) __request_region(&ioport_resource, (start), (n), (name), IORESOURCE_MUXED)
> +#define request_declared_muxed_region(res) __request_declared_region( \
> + &ioport_resource, \
> + (res), \
> + IORESOURCE_MUXED)
> #define __request_mem_region(start,n,name, excl) __request_region(&iomem_resource, (start), (n), (name), excl)
> #define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name), 0)
> #define request_mem_region_exclusive(start,n,name) \
> @@ -230,8 +238,14 @@ extern struct resource * __request_region(struct resource *,
> resource_size_t n,
> const char *name, int flags);
>
> +extern struct resource *__request_declared_region(struct resource *parent,
> + struct resource *res, int flags);
> +
> /* Compatibility cruft */
> #define release_region(start,n) __release_region(&ioport_resource, (start), (n))
> +#define release_declared_region(res) __release_region(&ioport_resource, \
> + (res)->start, \
> + (res)->end - (res)->start + 1)
> #define release_mem_region(start,n) __release_region(&iomem_resource, (start), (n))
>
> extern void __release_region(struct resource *, resource_size_t,
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 54ba6de3757c..05db9c4e3992 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -184,6 +184,9 @@ static void free_resource(struct resource *res)
> if (!res)
> return;
>
> + if (!(res->flags & IORESOURCE_ALLOCATED))
> + return;
> +
> if (!PageSlab(virt_to_head_page(res))) {
> spin_lock(&bootmem_resource_lock);
> res->sibling = bootmem_resource_free;
> @@ -210,6 +213,8 @@ static struct resource *alloc_resource(gfp_t flags)
> else
> res = kzalloc(sizeof(struct resource), flags);
>
> + res->flags = IORESOURCE_ALLOCATED;
> +
kzalloc() can fail, thus res can be NULL.
> return res;
> }
>
> @@ -1128,8 +1133,19 @@ resource_size_t resource_alignment(struct resource *res)
> * the IO flag meanings (busy etc).
> *
> * request_region creates a new busy region.
> + * The resource descriptor is allocated by this function.
> + *
> + * request_declared_region creates a new busy region
> + * described in an existing resource descriptor.
> + *
> + * request_muxed_region creates a new shared busy region.
> + * The resource descriptor is allocated by this function.
> + *
> + * request_declared_muxed_region creates a new shared busy region
> + * described in an existing resource descriptor.
> *
> * release_region releases a matching busy region.
> + * The region is only freed if it was allocated.
> */
>
> static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait);
> @@ -1146,7 +1162,6 @@ struct resource * __request_region(struct resource *parent,
> resource_size_t start, resource_size_t n,
> const char *name, int flags)
> {
> - DECLARE_WAITQUEUE(wait, current);
> struct resource *res = alloc_resource(GFP_KERNEL);
>
> if (!res)
> @@ -1156,6 +1171,26 @@ struct resource * __request_region(struct resource *parent,
> res->start = start;
> res->end = start + n - 1;
>
> + if (!__request_declared_region(parent, res, flags)) {
> + free_resource(res);
> + res = NULL;
> + }
> +
> + return res;
> +}
> +EXPORT_SYMBOL(__request_region);
> +
> +/**
> + * __request_declared_region - create a new busy resource region
> + * @parent: parent resource descriptor
> + * @res: child resource descriptor
> + * @flags: IO resource flags
> + */
> +struct resource *__request_declared_region(struct resource *parent,
> + struct resource *res, int flags)
> +{
> + DECLARE_WAITQUEUE(wait, current);
> +
> write_lock(&resource_lock);
>
> for (;;) {
> @@ -1184,14 +1219,13 @@ struct resource * __request_region(struct resource *parent,
> continue;
> }
> /* Uhhuh, that didn't work out.. */
> - free_resource(res);
> res = NULL;
> break;
> }
> write_unlock(&resource_lock);
> return res;
> }
> -EXPORT_SYMBOL(__request_region);
> +EXPORT_SYMBOL(__request_declared_region);
>
> /**
> * __release_region - release a previously reserved resource region
> --
> 2.13.6
>
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