diff options
| author | Simon Guinot <simon.guinot@sequanux.org> | 2015-09-10 00:15:18 +0200 |
|---|---|---|
| committer | Luis Henriques <luis.henriques@canonical.com> | 2016-03-04 10:26:43 +0000 |
| commit | c40374d56523e24431dc420ecac7e04364860087 (patch) | |
| tree | 48f44e274d374f8d802b91bc565aac688471f54b /kernel | |
| parent | c0c009a095deb004ed422c10e02054e15ed4a340 (diff) | |
kernel/resource.c: fix muxed resource handling in __request_region()
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: Luis Henriques <luis.henriques@canonical.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/resource.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/resource.c b/kernel/resource.c index 3c2237ac32db..db48bab5ea18 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -957,9 +957,10 @@ 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); |