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authorPrarit Bhargava <prarit@redhat.com>2014-06-04 16:12:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:54:21 -0700
commit7b0b73d76651e5f88c88b76efa18d719f832bf6f (patch)
tree6a3fc7c9bf1e2efbd4c4188e3598cc786c541b7b /init
parentd62cf81524304396276f6aaa5cd7ce62f6f65110 (diff)
init/main.c: add initcall_blacklist kernel parameter
When a module is built into the kernel the module_init() function becomes an initcall. Sometimes debugging through dynamic debug can help, however, debugging built in kernel modules is typically done by changing the .config, recompiling, and booting the new kernel in an effort to determine exactly which module caused a problem. This patchset can be useful stand-alone or combined with initcall_debug. There are cases where some initcalls can hang the machine before the console can be flushed, which can make initcall_debug output inaccurate. Having the ability to skip initcalls can help further debugging of these scenarios. Usage: initcall_blacklist=<list of comma separated initcalls> ex) added "initcall_blacklist=sgi_uv_sysfs_init" as a kernel parameter and the log contains: blacklisting initcall sgi_uv_sysfs_init ... ... initcall sgi_uv_sysfs_init blacklisted ex) added "initcall_blacklist=foo_bar,sgi_uv_sysfs_init" as a kernel parameter and the log contains: blacklisting initcall foo_bar blacklisting initcall sgi_uv_sysfs_init ... ... initcall sgi_uv_sysfs_init blacklisted [akpm@linux-foundation.org: tweak printk text] Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: Richard Weinberger <richard.weinberger@gmail.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Josh Boyer <jwboyer@fedoraproject.org> Cc: Rob Landley <rob@landley.net> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'init')
-rw-r--r--init/main.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/init/main.c b/init/main.c
index 9d3a7b84de5c..8ac3833f2bdf 100644
--- a/init/main.c
+++ b/init/main.c
@@ -77,6 +77,7 @@
#include <linux/sched_clock.h>
#include <linux/context_tracking.h>
#include <linux/random.h>
+#include <linux/list.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -665,6 +666,70 @@ static void __init do_ctors(void)
bool initcall_debug;
core_param(initcall_debug, initcall_debug, bool, 0644);
+#ifdef CONFIG_KALLSYMS
+struct blacklist_entry {
+ struct list_head next;
+ char *buf;
+};
+
+static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
+
+static int __init initcall_blacklist(char *str)
+{
+ char *str_entry;
+ struct blacklist_entry *entry;
+
+ /* str argument is a comma-separated list of functions */
+ do {
+ str_entry = strsep(&str, ",");
+ if (str_entry) {
+ pr_debug("blacklisting initcall %s\n", str_entry);
+ entry = alloc_bootmem(sizeof(*entry));
+ entry->buf = alloc_bootmem(strlen(str_entry) + 1);
+ strcpy(entry->buf, str_entry);
+ list_add(&entry->next, &blacklisted_initcalls);
+ }
+ } while (str_entry);
+
+ return 0;
+}
+
+static bool __init_or_module initcall_blacklisted(initcall_t fn)
+{
+ struct list_head *tmp;
+ struct blacklist_entry *entry;
+ char *fn_name;
+
+ fn_name = kasprintf(GFP_KERNEL, "%pf", fn);
+ if (!fn_name)
+ return false;
+
+ list_for_each(tmp, &blacklisted_initcalls) {
+ entry = list_entry(tmp, struct blacklist_entry, next);
+ if (!strcmp(fn_name, entry->buf)) {
+ pr_debug("initcall %s blacklisted\n", fn_name);
+ kfree(fn_name);
+ return true;
+ }
+ }
+
+ kfree(fn_name);
+ return false;
+}
+#else
+static int __init initcall_blacklist(char *str)
+{
+ pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\n");
+ return 0;
+}
+
+static bool __init_or_module initcall_blacklisted(initcall_t fn)
+{
+ return false;
+}
+#endif
+__setup("initcall_blacklist=", initcall_blacklist);
+
static int __init_or_module do_one_initcall_debug(initcall_t fn)
{
ktime_t calltime, delta, rettime;
@@ -689,6 +754,9 @@ int __init_or_module do_one_initcall(initcall_t fn)
int ret;
char msgbuf[64];
+ if (initcall_blacklisted(fn))
+ return -EPERM;
+
if (initcall_debug)
ret = do_one_initcall_debug(fn);
else

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