| Message ID | 200812042151.58676.arnd@arndb.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Thursday 04 December 2008, Arnd Bergmann wrote: > The read-mask function assumes that it is running in 32-bit mode, > by addressing the bitmask as a series of int values, instead of > longs. This is broken as can easily be reproduced by running numademo > on a bit-endian 64-bit system. > > Changing the addressing to use 'long' values fixes the problem. Unfortunately, this is still wrong, as it tries recreating a kernel data structure that is represented as a series of 'int' values, just in a different order. What we really need is the reverse of bitmap_scnprintf from linux/lib/bitmap.c. I don't have access to a little-endian NUMA machine with more than 64 CPUs, so I really don't want to send another embarrassingly wrong patch for this. Can anyone else try to come up with a version that handles endianess correctly and still works on x86-64? Arnd <><
diff --git a/libnuma.c b/libnuma.c index 4d26093..9a9fbbe 100755 --- a/libnuma.c +++ b/libnuma.c @@ -376,9 +376,9 @@ read_mask(char *s, struct bitmask *bmp) { char *end = s; char *prevend; - unsigned int *start = (unsigned int *)bmp->maskp; - unsigned int *p = start; - unsigned int *q; + unsigned long *start = bmp->maskp; + unsigned long *p = start; + unsigned long *q; unsigned int i; unsigned int n = 0; @@ -415,14 +415,14 @@ read_mask(char *s, struct bitmask *bmp) } /* Poor mans fls() */ - for(i = 31; i >= 0; i--) + for(i = sizeof(long) * 8 - 1; i >= 0; i--) if (test_bit(i, start + n)) break; /* * Return the last bit set */ - return ((sizeof(unsigned int)*8) * n) + i; + return ((sizeof(unsigned long)*8) * n) + i; } /*
The read-mask function assumes that it is running in 32-bit mode, by addressing the bitmask as a series of int values, instead of longs. This is broken as can easily be reproduced by running numademo on a bit-endian 64-bit system. Changing the addressing to use 'long' values fixes the problem. Reported-by: Mijo Safradin <safradin@de.ibm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- libnuma.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-)