diff options
| author | Simon Guinot <simon.guinot@sequanux.org> | 2015-09-10 00:15:18 +0200 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-04-13 20:44:38 -0400 |
| commit | 805d5d71d712b47812b75b43f7805a9ca9580300 (patch) | |
| tree | c55f6b7c1811941e70366cc4778e5b64341b9619 /kernel | |
| parent | 720db91c2e5fb56544f935bd8d62d07faedbfb2a (diff) | |
| download | linux-rt-805d5d71d712b47812b75b43f7805a9ca9580300.tar.gz | |
kernel/resource.c: fix muxed resource handling in __request_region()
[ Upstream commit 59ceeaaf355fa0fb16558ef7c24413c804932ada ]
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>
Signed-off-by: Sasha Levin <sasha.levin@oracle.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 0bcebffc4e77..e3011e1a5c8d 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -1073,9 +1073,10 @@ 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); |