Problems this addresses:
* After the allocation of t_info fails, the path the code takes tries to
free t_info. Jump past that part instead.
* The failure code assumes that unused data is zero; but the structure
is never initialized. Zero the structure before using it.
* The t_info pages are shared with dom0 before we know that the whole
operation will succeed, and not un-shared afterwards. Don''t share the
pages until we know the whole thing will succeed.
Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
diff -r 08ae34c0c162 -r f89c5bdf26a1 xen/common/trace.c
--- a/xen/common/trace.c Wed Apr 11 11:36:43 2012 +0100
+++ b/xen/common/trace.c Thu Apr 12 12:26:29 2012 +0100
@@ -187,14 +187,12 @@ static int alloc_trace_bufs(unsigned int
t_info = alloc_xenheap_pages(get_order_from_pages(t_info_pages), 0);
if ( t_info == NULL )
- goto out_dealloc_t_info;
+ goto out_fail;
+
+ memset(t_info, 0, t_info_pages*PAGE_SIZE);
t_info_mfn_list = (uint32_t *)t_info;
- for(i = 0; i < t_info_pages; i++)
- share_xen_page_with_privileged_guests(
- virt_to_page(t_info) + i, XENSHARE_readonly);
-
t_info->tbuf_size = pages;
/*
@@ -247,6 +245,11 @@ static int alloc_trace_bufs(unsigned int
}
}
+ /* Finally, share the t_info page */
+ for(i = 0; i < t_info_pages; i++)
+ share_xen_page_with_privileged_guests(
+ virt_to_page(t_info) + i, XENSHARE_readonly);
+
data_size = (pages * PAGE_SIZE - sizeof(struct t_buf));
t_buf_highwater = data_size >> 1; /* 50% high water */
opt_tbuf_size = pages;
@@ -272,9 +275,9 @@ out_dealloc:
free_xenheap_pages(mfn_to_virt(mfn), 0);
}
}
-out_dealloc_t_info:
free_xenheap_pages(t_info, get_order_from_pages(t_info_pages));
t_info = NULL;
+out_fail:
printk(XENLOG_WARNING "xentrace: allocation failed! Tracing
disabled.\n");
return -ENOMEM;
}