summaryrefslogtreecommitdiff
path: root/include/linux/jump_label.h
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2017-03-07 09:37:28 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-03-07 09:37:28 -0800
commitf26db9649af36b8eb76850108113d4056f494537 (patch)
treec465767c8112cf5ebc7eb30ba9f19a770906560c /include/linux/jump_label.h
parentc1ae3cfa0e89fa1a7ecc4c99031f5e9ae99d9201 (diff)
parent65a50c656276b0846bea09dd011c0a3d35b77f3e (diff)
Merge tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt: "There was some breakage with the changes for jump labels in the 4.11 merge window: - powerpc broke as jump labels uses the two LSB bits as flags in initialization. A check was added to make sure that all jump label entries were 4 bytes aligned, but powerpc didn't work that way for modules. Adding an alignment in the module linker script appeared to be the best solution. - Jump labels also added an anonymous union to access those LSB bits as a normal long. But because this structure had static initialization, it broke older compilers that could not statically initialize anonymous unions without brackets. - The command line parameter for setting function graph filter broke the "EMPTY_HASH" descriptor by modifying it instead of creating a new hash to hold the entries. - The command line parameter ftrace_graph_max_depth was added to allow its setting at boot time. It uses existing code and only the command line hook was added. This is not really a fix, but as it uses existing code without affecting anything else, I added it to this release. It was ready before the merge window closed, but I wanted to let it sit in linux-next for a couple of days first" * tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace/graph: Add ftrace_graph_max_depth kernel parameter tracing: Add #undef to fix compile error jump_label: Add comment about initialization order for anonymous unions jump_label: Fix anonymous union initialization module: set __jump_table alignment to 8 ftrace/graph: Do not modify the EMPTY_HASH for the function_graph filter tracing: Fix code comment for ftrace_ops_get_func()
Diffstat (limited to 'include/linux/jump_label.h')
-rw-r--r--include/linux/jump_label.h11
1 files changed, 9 insertions, 2 deletions
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 8e06d758ee48..2afd74b9d844 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -90,6 +90,13 @@ extern bool static_key_initialized;
struct static_key {
atomic_t enabled;
/*
+ * Note:
+ * To make anonymous unions work with old compilers, the static
+ * initialization of them requires brackets. This creates a dependency
+ * on the order of the struct with the initializers. If any fields
+ * are added, STATIC_KEY_INIT_TRUE and STATIC_KEY_INIT_FALSE may need
+ * to be modified.
+ *
* bit 0 => 1 if key is initially true
* 0 if initially false
* bit 1 => 1 if points to struct static_key_mod
@@ -166,10 +173,10 @@ extern void static_key_disable(struct static_key *key);
*/
#define STATIC_KEY_INIT_TRUE \
{ .enabled = { 1 }, \
- .entries = (void *)JUMP_TYPE_TRUE }
+ { .entries = (void *)JUMP_TYPE_TRUE } }
#define STATIC_KEY_INIT_FALSE \
{ .enabled = { 0 }, \
- .entries = (void *)JUMP_TYPE_FALSE }
+ { .entries = (void *)JUMP_TYPE_FALSE } }
#else /* !HAVE_JUMP_LABEL */