From 7a223440b71e664b31505eba0a064566d03d7e2d Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Wed, 3 Feb 2010 09:35:56 +0000 Subject: [PATCH] xentrace: Clear lost records when disabling tracing This patch clears the "lost records" flag on each cpu when tracing is disabled. Without this patch, the next time tracing starts, cpus with lost records will generate lost record traces, even though buffers are empty and no tracing has recently happened. Signed-off-by: George Dunlap --- xen/common/trace.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/xen/common/trace.c b/xen/common/trace.c index d8eaf669ff..44cc8341d0 100644 --- a/xen/common/trace.c +++ b/xen/common/trace.c @@ -316,11 +316,26 @@ int tb_control(xen_sysctl_tbuf_op_t *tbc) tb_init_done = 1; break; case XEN_SYSCTL_TBUFOP_disable: + { /* * Disable trace buffers. Just stops new records from being written, * does not deallocate any memory. */ + int i; + tb_init_done = 0; + wmb(); + /* Clear any lost-record info so we don't get phantom lost records next time we + * start tracing. Grab the lock to make sure we're not racing anyone. After this + * hypercall returns, no more records should be placed into the buffers. */ + for_each_online_cpu(i) + { + int flags; + spin_lock_irqsave(&per_cpu(t_lock, i), flags); + per_cpu(lost_records, i)=0; + spin_unlock_irqrestore(&per_cpu(t_lock, i), flags); + } + } break; default: rc = -EINVAL; -- 2.30.2