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raw | patch | inline | side by side (parent: 0fbc074)
author | Simon Guinot <simon.guinot@sequanux.org> | |
Wed, 9 Sep 2015 22:15:18 +0000 (00:15 +0200) | ||
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
Thu, 3 Mar 2016 23:06:53 +0000 (15:06 -0800) |
commit 59ceeaaf355fa0fb16558ef7c24413c804932ada upstream.
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/resource.c | patch | blob | history |
diff --git a/kernel/resource.c b/kernel/resource.c
index 3f285dce9347191537b8d13f8db53f869d4744ad..449282e48bb1e7edee675e7965a284d3ac94cdab 100644 (file)
--- a/kernel/resource.c
+++ b/kernel/resource.c
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);