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authorDavid Gibson <david@gibson.dropbear.id.au>2007-02-28 14:12:29 +1100
committerPaul Mackerras <paulus@samba.org>2007-03-08 15:43:28 +1100
commiteb6de2863750e696201780283e4c9ada19b4728e (patch)
tree18a4787a4857216313d5836523238e4a9ef14f9e /arch/powerpc/mm/lmb.c
parent83ddcf5d364be7b1d8c214d2dd97753e1df589cd (diff)
[POWERPC] Allow duplicate lmb_reserve() calls
At present calling lmb_reserve() (and hence lmb_add_region()) twice for exactly the same memory region will cause strange behaviour. This makes life difficult when booting from a flat device tree with memory reserve map. Which regions are automatically reserved by the kernel has changed over time, so it's quite possible a newer kernel could attempt to auto-reserve a region which is also explicitly listed in the device tree's reserve map, leading to trouble. This patch avoids the problem by making lmb_reserve() ignore a call to reserve a previously reserved region. It also removes a now redundant test designed to avoid one specific case of the problem noted above. At present, this patch deals only with duplicate reservations of an identical region. Attempting to reserve two different, but overlapping regions will still cause problems. I might post another patch later dealing with this case, but I'm avoiding it now since it is substantially more complicated to deal with, less likely to occur and more likely to indicate a genuine bug elsewhere if it does occur. Signed-off-by: David Gibson <dwg@au1.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/mm/lmb.c')
-rw-r--r--arch/powerpc/mm/lmb.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/mm/lmb.c b/arch/powerpc/mm/lmb.c
index 716a2906a24..e3a1e8dc536 100644
--- a/arch/powerpc/mm/lmb.c
+++ b/arch/powerpc/mm/lmb.c
@@ -146,6 +146,10 @@ static long __init lmb_add_region(struct lmb_region *rgn, unsigned long base,
unsigned long rgnbase = rgn->region[i].base;
unsigned long rgnsize = rgn->region[i].size;
+ if ((rgnbase == base) && (rgnsize == size))
+ /* Already have this region, so we're done */
+ return 0;
+
adjacent = lmb_addrs_adjacent(base,size,rgnbase,rgnsize);
if ( adjacent > 0 ) {
rgn->region[i].base -= size;