No functional changes, move reuse/attach code into the new helpers.
Microptimizations:
- check ->utrace_flags before trying to re-use the self-detaching
engine
- if ptrace_reuse_engine() finds engine and ->resume != UTRACE_DETACH,
we can just return EPERM without trying UTRACE_ATTACH_CREATE.
---
kernel/ptrace.c | 96 +++++++++++++++++++++++++++++++++++---------------------
1 file changed, 61 insertions(+), 35 deletions(-)
--- PU/kernel/ptrace.c~86_CLEANUP_ATTACH_REUSE 2009-10-13 14:15:48.000000000
+0200
+++ PU/kernel/ptrace.c 2009-10-13 17:36:05.000000000 +0200
@@ -421,6 +421,64 @@ static const struct utrace_engine_ops pt
.release = ptrace_release,
};
+static struct utrace_engine *
+ptrace_reuse_engine(struct task_struct *tracee)
+{
+ struct utrace_engine *engine;
+ struct ptrace_context *context;
+ int err = -EPERM;
+
+ engine = ptrace_lookup_engine(tracee);
+ if (IS_ERR(engine))
+ return engine;
+
+ context = ptrace_context(engine);
+ if (unlikely(context->resume == UTRACE_DETACH)) {
+ /* we rely on ->cred_guard_mutex */
+ context->resume = UTRACE_RESUME;
+ /* make sure we don't race with ptrace_report_signal() */
+ err = utrace_barrier(tracee, engine);
+ WARN_ON(!err != (engine->ops == &ptrace_utrace_ops));
+ if (!err)
+ return engine;
+ }
+
+ utrace_engine_put(engine);
+ return ERR_PTR(err);
+}
+
+static struct utrace_engine *
+ptrace_attach_engine(struct task_struct *tracee)
+{
+ struct utrace_engine *engine;
+ struct ptrace_context *context;
+
+ if (unlikely(task_utrace_flags(tracee))) {
+ engine = ptrace_reuse_engine(tracee);
+ if (!IS_ERR(engine) || IS_ERR(engine) == -EPERM)
+ return engine;
+ }
+
+ context = kzalloc(sizeof(*context), GFP_KERNEL);
+ if (unlikely(!context))
+ return ERR_PTR(-ENOMEM);
+
+ context->resume = UTRACE_RESUME;
+
+ engine = utrace_attach_task(tracee, UTRACE_ATTACH_CREATE |
+ UTRACE_ATTACH_EXCLUSIVE |
+ UTRACE_ATTACH_MATCH_OPS,
+ &ptrace_utrace_ops, context);
+ if (unlikely(IS_ERR(engine))) {
+ if (engine != ERR_PTR(-ESRCH) &&
+ engine != ERR_PTR(-ERESTARTNOINTR))
+ engine = ERR_PTR(-EPERM);
+ kfree(context);
+ }
+
+ return engine;
+}
+
static inline int __ptrace_set_options(struct task_struct *target,
struct utrace_engine *engine,
unsigned long options)
@@ -446,44 +504,12 @@ static inline int __ptrace_set_options(s
*/
static int ptrace_attach_task(struct task_struct *tracee, int options)
{
- struct ptrace_context *context;
struct utrace_engine *engine;
int err;
- engine = ptrace_lookup_engine(tracee);
- if (!IS_ERR(engine)) {
- context = ptrace_context(engine);
- if (context->resume == UTRACE_DETACH) {
- /* we rely on ->cred_guard_mutex */
- context->resume = UTRACE_RESUME;
- /*
- * Make sure we don't race with ptrace_report_signal()
- */
- err = utrace_barrier(tracee, engine);
- if (!err)
- goto finish;
- }
- utrace_engine_put(engine);
- }
-
- context = kzalloc(sizeof(*context), GFP_KERNEL);
- if (unlikely(!context))
- return -ENOMEM;
-
- context->resume = UTRACE_RESUME;
-
- engine = utrace_attach_task(tracee, UTRACE_ATTACH_CREATE |
- UTRACE_ATTACH_EXCLUSIVE |
- UTRACE_ATTACH_MATCH_OPS,
- &ptrace_utrace_ops, context);
- if (unlikely(IS_ERR(engine))) {
- err = PTR_ERR(engine);
- if (err != -ESRCH && err != -ERESTARTNOINTR)
- err = -EPERM;
- kfree(context);
- return err;
- }
-finish:
+ engine = ptrace_attach_engine(tracee);
+ if (IS_ERR(engine))
+ return PTR_ERR(engine);
/*
* It can fail only if the tracee is dead, the caller
* must notice this before setting PT_PTRACED.
