[patch 13/27] : Fix sparc64 cpu cross call hangs.

Greg KH
2008-02-02T00:28:55Z

[-- Attachment #1: fix-sparc64-cpu-cross-call-hangs.patch --]
[-- Type: text/plain, Size: 2328 bytes --]

2.6.22-stable review patch. If anyone has any objections, please let us
know.

------------------
From: "David S. Miller" <davem@davemloft.net>

[SPARC64]: Fix endless loop in cheetah_xcall_deliver().

[ Upsteam commit: 0de56d1ab83323d604d95ca193dcbd28388dbabb ]

We need to mask out the proper bits when testing the dispatch status
register else we can see unrelated NACK bits from previous cross call
sends.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
arch/sparc64/kernel/smp.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)

--- a/arch/sparc64/kernel/smp.c
+++ b/arch/sparc64/kernel/smp.c
@@ -403,7 +403,7 @@ static __inline__ void spitfire_xcall_de
*/
static void cheetah_xcall_deliver(u64 data0, u64 data1, u64 data2, cpumask_t mask)
{
- u64 pstate, ver;
+ u64 pstate, ver, busy_mask;
int nack_busy_id, is_jbus, need_more;

if (cpus_empty(mask))
@@ -435,14 +435,20 @@ retry:
"i" (ASI_INTR_W));

nack_busy_id = 0;
+ busy_mask = 0;
{
int i;

for_each_cpu_mask(i, mask) {
u64 target = (i << 14) | 0x70;

- if (!is_jbus)
+ if (is_jbus) {
+ busy_mask |= (0x1UL << (i * 2));
+ } else {
target |= (nack_busy_id << 24);
+ busy_mask |= (0x1UL <<
+ (nack_busy_id * 2));
+ }
__asm__ __volatile__(
"stxa %%g0, [%0] %1\n\t"
"membar #Sync\n\t"
@@ -458,15 +464,16 @@ retry:

/* Now, poll for completion. */
{
- u64 dispatch_stat;
+ u64 dispatch_stat, nack_mask;
long stuck;

stuck = 100000 * nack_busy_id;
+ nack_mask = busy_mask << 1;
do {
__asm__ __volatile__("ldxa [%%g0] %1, %0"
: "=r" (dispatch_stat)
: "i" (ASI_INTR_DISPATCH_STAT));
- if (dispatch_stat == 0UL) {
+ if (!(dispatch_stat & (busy_mask | nack_mask))) {
__asm__ __volatile__("wrpr %0, 0x0, %%pstate"
: : "r" (pstate));
if (unlikely(need_more)) {
@@ -483,12 +490,12 @@ retry:
}
if (!--stuck)
break;
- } while (dispatch_stat & 0x5555555555555555UL);
+ } while (dispatch_stat & busy_mask);

__asm__ __volatile__("wrpr %0, 0x0, %%pstate"
: : "r" (pstate));

- if ((dispatch_stat & ~(0x5555555555555555UL)) == 0) {
+ if (dispatch_stat & busy_mask) {
/* Busy bits will not clear, continue instead
* of freezing up on this cpu.
*/

--