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authorSimon Guinot <simon.guinot@sequanux.org>2015-09-10 00:15:18 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-20 08:57:52 -0800
commit59ceeaaf355fa0fb16558ef7c24413c804932ada (patch)
treef44384241bd98a08194039f112bd8f1e22c417cb
parent020ecbba0548cefc91c3c5de32c28a62bcf37ed9 (diff)
kernel/resource.c: fix muxed resource handling in __request_region()
In __request_region, if a conflict with a BUSY and MUXED resource is detected, then the caller goes to sleep and waits for the resource to be released. A pointer on the conflicting resource is kept. At wake-up this pointer is used as a parent to retry to request the region. A first problem is that this pointer might well be invalid (if for example the conflicting resource have already been freed). Another problem is that the next call to __request_region() fails to detect a remaining conflict. The previously conflicting resource is passed as a parameter and __request_region() will look for a conflict among the children of this resource and not at the resource itself. It is likely to succeed anyway, even if there is still a conflict. Instead, the parent of the conflicting resource should be passed to __request_region(). As a fix, this patch doesn't update the parent resource pointer in the case we have to wait for a muxed region right after. Reported-and-tested-by: Vincent Pelletier <plr.vincent@gmail.com> Signed-off-by: Simon Guinot <simon.guinot@sequanux.org> Tested-by: Vincent Donnefort <vdonnefort@gmail.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/resource.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index 09c0597840b0..3669d1bfc425 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1083,9 +1083,10 @@ struct resource * __request_region(struct resource *parent,
if (!conflict)
break;
if (conflict != parent) {
- parent = conflict;
- if (!(conflict->flags & IORESOURCE_BUSY))
+ if (!(conflict->flags & IORESOURCE_BUSY)) {
+ parent = conflict;
continue;
+ }
}
if (conflict->flags & flags & IORESOURCE_MUXED) {
add_wait_queue(&muxed_resource_wait, &wait);