Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir@xen.org>
# Date 1292530691 0
# Node ID eebc0881bdf7dc37e07102101d76c47892623b37
# Parent 4cf3919db1b5b8d04f43887b389dbf9d4191feee
xentrace: Clean up initialisation.

Allocate no memory and print no debug messages when disabled.

Signed-off-by: Keir Fraser <keir@xen.org>
xen-unstable changeset: 22567:f5f3cf4e001f
xen-unstable date: Thu Dec 16 20:07:03 2010 +0000
---
xen/common/trace.c | 118 +++++++++++++++++++++++------------------------------
1 files changed, 53 insertions(+), 65 deletions(-)

diff -r 4cf3919db1b5 -r eebc0881bdf7 xen/common/trace.c
--- a/xen/common/trace.c Thu Dec 16 20:13:47 2010 +0000
+++ b/xen/common/trace.c Thu Dec 16 20:18:11 2010 +0000
@@ -79,14 +79,8 @@ static u32 tb_event_mask = TRC_ALL;

static void calc_tinfo_first_offset(void)
{
- int offset_in_bytes;
-
- offset_in_bytes = offsetof(struct t_info, mfn_offset[NR_CPUS]);
-
+ int offset_in_bytes = offsetof(struct t_info, mfn_offset[NR_CPUS]);
t_info_first_offset = fit_to_type(uint32_t, offset_in_bytes);
-
- gdprintk(XENLOG_INFO, "%s: NR_CPUs %d, offset_in_bytes %d, t_info_first_offset %u\n",
- __func__, NR_CPUS, offset_in_bytes, (unsigned)t_info_first_offset);
}

/**
@@ -121,20 +115,36 @@ static int alloc_trace_bufs(void)
int i, cpu, order;
unsigned long nr_pages;
/* Start after a fixed-size array of NR_CPUS */
- uint32_t *t_info_mfn_list = (uint32_t *)t_info;
- int offset = t_info_first_offset;
-
- BUG_ON(check_tbuf_size(opt_tbuf_size));
+ uint32_t *t_info_mfn_list;
+ int offset;

if ( opt_tbuf_size == 0 )
return -EINVAL;

- if ( !t_info )
- {
- printk("%s: t_info not allocated, cannot allocate trace buffers!\n",
- __func__);
+ if ( check_tbuf_size(opt_tbuf_size) )
+ {
+ printk("Xen trace buffers: tb size %d too large. "
+ "Tracing disabled.\n",
+ opt_tbuf_size);
return -EINVAL;
}
+
+ /* t_info size is fixed for now. Currently this works great, so there
+ * seems to be no need to make it dynamic. */
+ t_info = alloc_xenheap_pages(get_order_from_pages(T_INFO_PAGES), 0);
+ if ( t_info == NULL )
+ {
+ printk("Xen trace buffers: t_info allocation failed! "
+ "Tracing disabled.\n");
+ return -ENOMEM;
+ }
+
+ for ( i = 0; i < T_INFO_PAGES; i++ )
+ share_xen_page_with_privileged_guests(
+ virt_to_page(t_info) + i, XENSHARE_readonly);
+
+ t_info_mfn_list = (uint32_t *)t_info;
+ offset = t_info_first_offset;

t_info->tbuf_size = opt_tbuf_size;
printk(XENLOG_INFO "tbuf_size %d\n", t_info->tbuf_size);
@@ -241,7 +251,7 @@ static int tb_set_size(int size)



- if ( (opt_tbuf_size != 0) )
+ if ( opt_tbuf_size != 0 )
{
if ( size != opt_tbuf_size )
gdprintk(XENLOG_INFO, "tb_set_size from %d to %d not implemented\n",
@@ -252,20 +262,16 @@ static int tb_set_size(int size)
if ( size <= 0 )
return -EINVAL;

- if ( check_tbuf_size(size) )
- {
- gdprintk(XENLOG_INFO, "tb size %d too large\n", size);
- return -EINVAL;
- }
-
opt_tbuf_size = size;

- if ( (ret = alloc_trace_bufs()) == 0 )
- printk("Xen trace buffers: initialized\n");
- else
+ if ( (ret = alloc_trace_bufs()) != 0 )
+ {
opt_tbuf_size = 0;
-
- return ret;
+ return ret;
+ }
+
+ printk("Xen trace buffers: initialized\n");
+ return 0;
}

int trace_will_trace_event(u32 event)
@@ -308,49 +314,31 @@ void __init init_trace_bufs(void)
/* Calculate offset in u32 of first mfn */
calc_tinfo_first_offset();

- /* t_info size fixed at 2 pages for now. That should be big enough / small enough
- * until it's worth making it dynamic. */
- t_info = alloc_xenheap_pages(1, 0);
-
- if ( t_info == NULL )
- {
- printk("Xen trace buffers: t_info allocation failed! Tracing disabled.\n");
- return;
- }
-
- for(i = 0; i < NR_CPUS; i++)
+ /* Per-cpu t_lock initialisation. */
+ for ( i = 0; i < NR_CPUS; i++ )
spin_lock_init(&per_cpu(t_lock, i));

- for(i=0; i<T_INFO_PAGES; i++)
- share_xen_page_with_privileged_guests(
- virt_to_page(t_info) + i, XENSHARE_readonly);
-
if ( opt_tbuf_size == 0 )
{
printk("Xen trace buffers: disabled\n");
- return;
- }
- else if ( check_tbuf_size(opt_tbuf_size) )
- {
- gdprintk(XENLOG_INFO, "Xen trace buffers: "
- "tb size %d too large, disabling\n",
- opt_tbuf_size);
- opt_tbuf_size = 0;
- }
-
- if ( alloc_trace_bufs() == 0 )
- {
- printk("Xen trace buffers: initialised\n");
- wmb(); /* above must be visible before tb_init_done flag set */
- tb_init_done = 1;
- }
- else
- {
- gdprintk(XENLOG_INFO, "Xen trace buffers: "
- "allocation size %d failed, disabling\n",
- opt_tbuf_size);
- opt_tbuf_size = 0;
- }
+ goto fail;
+ }
+
+ if ( alloc_trace_bufs() != 0 )
+ {
+ dprintk(XENLOG_INFO, "Xen trace buffers: "
+ "allocation size %d failed, disabling\n",
+ opt_tbuf_size);
+ goto fail;
+ }
+
+ printk("Xen trace buffers: initialised\n");
+ wmb(); /* above must be visible before tb_init_done flag set */
+ tb_init_done = 1;
+ return;
+
+ fail:
+ opt_tbuf_size = 0;
}

/**

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