diff options
Diffstat (limited to 'kernel/tracepoint.c')
| -rw-r--r-- | kernel/tracepoint.c | 80 |
1 files changed, 64 insertions, 16 deletions
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index a170d83043a5..b65b2e7fd850 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -60,6 +60,12 @@ struct tp_probes { struct tracepoint_func probes[0]; }; +/* Called in removal of a func but failed to allocate a new tp_funcs */ +static void tp_stub_func(void) +{ + return; +} + static inline void *allocate_probes(int count) { struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) @@ -98,6 +104,7 @@ func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func, { struct tracepoint_func *old, *new; int nr_probes = 0; + int stub_funcs = 0; int pos = -1; if (WARN_ON(!tp_func->func)) @@ -114,14 +121,34 @@ func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func, if (old[nr_probes].func == tp_func->func && old[nr_probes].data == tp_func->data) return ERR_PTR(-EEXIST); + if (old[nr_probes].func == tp_stub_func) + stub_funcs++; } } - /* + 2 : one for new probe, one for NULL func */ - new = allocate_probes(nr_probes + 2); + /* + 2 : one for new probe, one for NULL func - stub functions */ + new = allocate_probes(nr_probes + 2 - stub_funcs); if (new == NULL) return ERR_PTR(-ENOMEM); if (old) { - if (pos < 0) { + if (stub_funcs) { + /* Need to copy one at a time to remove stubs */ + int probes = 0; + + pos = -1; + for (nr_probes = 0; old[nr_probes].func; nr_probes++) { + if (old[nr_probes].func == tp_stub_func) + continue; + if (pos < 0 && old[nr_probes].prio < prio) + pos = probes++; + new[probes++] = old[nr_probes]; + } + nr_probes = probes; + if (pos < 0) + pos = probes; + else + nr_probes--; /* Account for insertion */ + + } else if (pos < 0) { pos = nr_probes; memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); } else { @@ -155,8 +182,9 @@ static void *func_remove(struct tracepoint_func **funcs, /* (N -> M), (N > 1, M >= 0) probes */ if (tp_func->func) { for (nr_probes = 0; old[nr_probes].func; nr_probes++) { - if (old[nr_probes].func == tp_func->func && - old[nr_probes].data == tp_func->data) + if ((old[nr_probes].func == tp_func->func && + old[nr_probes].data == tp_func->data) || + old[nr_probes].func == tp_stub_func) nr_del++; } } @@ -175,14 +203,32 @@ static void *func_remove(struct tracepoint_func **funcs, /* N -> M, (N > 1, M > 0) */ /* + 1 for NULL */ new = allocate_probes(nr_probes - nr_del + 1); - if (new == NULL) - return ERR_PTR(-ENOMEM); - for (i = 0; old[i].func; i++) - if (old[i].func != tp_func->func - || old[i].data != tp_func->data) - new[j++] = old[i]; - new[nr_probes - nr_del].func = NULL; - *funcs = new; + if (new) { + for (i = 0; old[i].func; i++) + if ((old[i].func != tp_func->func + || old[i].data != tp_func->data) + && old[i].func != tp_stub_func) + new[j++] = old[i]; + new[nr_probes - nr_del].func = NULL; + *funcs = new; + } else { + /* + * Failed to allocate, replace the old function + * with calls to tp_stub_func. + */ + for (i = 0; old[i].func; i++) + if (old[i].func == tp_func->func && + old[i].data == tp_func->data) { + old[i].func = tp_stub_func; + /* Set the prio to the next event. */ + if (old[i + 1].func) + old[i].prio = + old[i + 1].prio; + else + old[i].prio = -1; + } + *funcs = old; + } } debug_print_probes(*funcs); return old; @@ -239,10 +285,12 @@ static int tracepoint_remove_func(struct tracepoint *tp, tp_funcs = rcu_dereference_protected(tp->funcs, lockdep_is_held(&tracepoints_mutex)); old = func_remove(&tp_funcs, func); - if (IS_ERR(old)) { - WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM); + if (WARN_ON_ONCE(IS_ERR(old))) return PTR_ERR(old); - } + + if (tp_funcs == old) + /* Failed allocating new tp_funcs, replaced func with stub */ + return 0; if (!tp_funcs) { /* Removed last function */ |