From 0cd2b0813aac660f5f7a6574083157a70c152dd5 Mon Sep 17 00:00:00 2001 From: Jack Steiner Date: Tue, 15 Dec 2009 16:48:17 -0800 Subject: 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/misc/sgi-gru/grukservices.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c index c13342dda5f..bfbf8fdbcd3 100644 --- a/drivers/misc/sgi-gru/grukservices.c +++ b/drivers/misc/sgi-gru/grukservices.c @@ -221,13 +221,21 @@ static int gru_free_kernel_contexts(void) 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 @@ static int gru_get_cpu_resources(int dsr_bytes, void **cb, void **dsr) 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; -- cgit v1.2.2