[PATCH 2/5 v2] Modify behaviour of request_*muxed_region()

From: ZoltÃn BÃszÃrmÃnyi
Date: Thu Jun 22 2017 - 09:22:26 EST

In order to make request_*muxed_region() behave more like
mutex_lock(), a possible failure case needs to be eliminated.
When drivers do not properly share the same I/O region, e.g.
one is using request_region() and the other is using
request_muxed_region(), the kernel didn't warn the user about it.
This change modifies IORESOURCE_MUXED behaviour so it always
goes to sleep waiting for the resuorce to be freed and the
inconsistent resource flag usage is logged with KERN_ERR.

v2: Fixed checkpatch.pl warnings and extended the comment
about request_declared_muxed_region.

Signed-off-by: ZoltÃn BÃszÃrmÃnyi <zboszor@xxxxx>
kernel/resource.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 2be7029..5df2731 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1125,6 +1125,7 @@ resource_size_t resource_alignment(struct resource *res)
* request_declared_muxed_region creates a new shared busy region
* described in an existing resource descriptor.
+ * It only returns if it succeeded.
* release_region releases a matching busy region.
* The region is only freed if it was allocated.
@@ -1191,7 +1192,10 @@ struct resource *__request_declared_region(struct resource *parent,
- if (conflict->flags & flags & IORESOURCE_MUXED) {
+ if (flags & IORESOURCE_MUXED) {
+ if (!(conflict->flags & IORESOURCE_MUXED))
+ pr_err("Resource conflict between muxed \"%s\" and non-muxed \"%s\" I/O regions!\n",
+ res->name, conflict->name);
add_wait_queue(&muxed_resource_wait, &wait);