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Date: Thu, 22 Jun 2017 15:21:30 +0200
From: Zoltán Böszörményi
<zboszor@...hu>
To: linux-kernel@...r.kernel.org
Cc: 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>,
Guenter Roeck <linux@...ck-us.net>, kernel@...ss.net,
wim@...ana.be, jlayton@...chiereds.net, marc.2377@...il.com,
cshorler@...glemail.com, wsa@...-dreams.de,
regressions@...mhuis.info,
Zoltán Böszörményi
<zboszor@...hu>
Subject: [PATCH 1/5 v2] Extend the request_region() infrastructure
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.
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 6230064..6ebcd39 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -52,6 +52,7 @@ 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) */
@@ -215,7 +216,14 @@ 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) \
@@ -227,8 +235,14 @@ 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 9b5f044..2be7029 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;
+
return res;
}
@@ -1110,8 +1115,19 @@ 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);
@@ -1128,7 +1144,6 @@ 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)
@@ -1138,6 +1153,26 @@ 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 (;;) {
@@ -1166,14 +1201,13 @@ 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
--
2.9.4
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