gru: fix bug in allocation of kernel contexts
Fix a bug in the assignment of GRU contexts used for kernel functions. If
a sleep occurs on the wait for a semaphore, the thread could switch cpus
and allocate resources on the wrong blade.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
index c13342d..bfbf8fd 100644
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -221,13 +221,21 @@
static struct gru_blade_state *gru_lock_kernel_context(int blade_id)
{
struct gru_blade_state *bs;
+ int bid;
STAT(lock_kernel_context);
- bs = gru_base[blade_id];
+again:
+ bid = blade_id < 0 ? uv_numa_blade_id() : blade_id;
+ bs = gru_base[bid];
+ /* Handle the case where migration occured while waiting for the sema */
down_read(&bs->bs_kgts_sema);
+ if (blade_id < 0 && bid != uv_numa_blade_id()) {
+ up_read(&bs->bs_kgts_sema);
+ goto again;
+ }
if (!bs->bs_kgts || !bs->bs_kgts->ts_gru)
- gru_load_kernel_context(bs, blade_id);
+ gru_load_kernel_context(bs, bid);
return bs;
}
@@ -256,7 +264,7 @@
BUG_ON(dsr_bytes > GRU_NUM_KERNEL_DSR_BYTES);
preempt_disable();
- bs = gru_lock_kernel_context(uv_numa_blade_id());
+ bs = gru_lock_kernel_context(-1);
lcpu = uv_blade_processor_id();
*cb = bs->kernel_cb + lcpu * GRU_HANDLE_STRIDE;
*dsr = bs->kernel_dsr + lcpu * GRU_NUM_KERNEL_DSR_BYTES;