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gru: fix bug in allocation of kernel contexts

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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>
This commit is contained in:
Jack Steiner 2009-12-15 16:48:17 -08:00 committed by Linus Torvalds
parent 5658366ab5
commit 0cd2b0813a
1 changed files with 11 additions and 3 deletions
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14
drivers/misc/sgi-gru/grukservices.c
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@ -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;