diff options
Diffstat (limited to 'tapsets.cxx')
| -rw-r--r-- | tapsets.cxx | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/tapsets.cxx b/tapsets.cxx index 3744c0cd..ab8f6c94 100644 --- a/tapsets.cxx +++ b/tapsets.cxx @@ -6932,7 +6932,11 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s) // register new uprobe s.op->newline() << "if (register_p && sup->spec_index < 0) {"; - s.op->newline(1) << "sup->spec_index = spec_index;"; + // PR6829: we need to check that the sup we're about to reuse is really completely free. + // See PR6829 notes below. + s.op->newline(1) << "if (sup->spec_index == -1 && sup->up.kdata != NULL) continue;"; + s.op->newline() << "else if (sup->spec_index == -2 && sup->urp.u.kdata != NULL) continue;"; + s.op->newline() << "sup->spec_index = spec_index;"; s.op->newline() << "if (sups->return_p) {"; s.op->newline(1) << "sup->urp.u.pid = tsk->tgid;"; s.op->newline() << "sup->urp.u.vaddr = relocation + sups->address;"; @@ -6968,15 +6972,22 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s) s.op->newline(1) << "#ifdef DEBUG_UPROBES"; s.op->newline() << "printk (KERN_WARNING \"uretprobe unregister pid %d addr %p\\n\", sup->up.pid, (void*) sup->up.vaddr);"; s.op->newline() << "#endif"; - s.op->newline() << "unregister_uretprobe (& sup->urp);"; + // NB: We must not actually uregister uprobes when a target process execs or exits; + // uprobes does that by itself asynchronously. We can reuse the up/urp struct after + // uprobes clears the sup->urp->kdata pointer. PR6829 + // s.op->newline() << "unregister_uretprobe (& sup->urp);"; + s.op->newline() << "sup->spec_index = -2;"; s.op->newline(-1) << "} else {"; s.op->newline(1) << "#ifdef DEBUG_UPROBES"; s.op->newline() << "printk (KERN_WARNING \"uprobe unregister pid %d addr %p\\n\", sup->urp.u.pid, (void*) sup->urp.u.vaddr);"; s.op->newline() << "#endif"; - s.op->newline() << "unregister_uprobe (& sup->up);"; + // NB: We must not actually unregister uprobes ... same as above, except that + // here it's the sup->up->kdata field that will get cleared. To tell the two + // cases apart, we use spec_index -2 vs -1. + // s.op->newline() << "unregister_uprobe (& sup->up);"; + s.op->newline() << "sup->spec_index = -1;"; s.op->newline(-1) << "}"; - s.op->newline(1) << "sup->spec_index = -1;"; - s.op->newline() << "handled_p = 1;"; + s.op->newline(1) << "handled_p = 1;"; s.op->newline() << "break;"; // exit to-free slot search s.op->newline(-1) << "}"; // if/else @@ -7037,6 +7048,9 @@ uprobe_derived_probe_group::emit_module_init (systemtap_session& s) s.op->newline() << "for (j=0; j<NUMUPROBES; j++) {"; s.op->newline(1) << "struct stap_uprobe *sup = & stap_uprobes[j];"; s.op->newline() << "sup->spec_index = -1;"; // free slot + // NB: we assume the rest of the struct (specificaly, sup->up) is + // initialized to zero. This is so that we can use + // sup->up->kdata = NULL for "really free!" PR 6829. s.op->newline(-1) << "}"; s.op->newline() << "mutex_init (& stap_uprobes_lock);"; @@ -7077,6 +7091,8 @@ uprobe_derived_probe_group::emit_module_exit (systemtap_session& s) s.op->newline(1) << "#ifdef DEBUG_UPROBES"; s.op->newline() << "printk (KERN_WARNING \"uretprobe unregister2 index %d pid %d addr %p\\n\", sup->spec_index, sup->up.pid, (void*) sup->up.vaddr);"; s.op->newline() << "#endif"; + // NB: PR6829 does not change that we still need to unregister at + // *this* time -- when the script as a whole exits. s.op->newline() << "unregister_uretprobe (& sup->urp);"; s.op->newline(-1) << "} else {"; s.op->newline(1) << "#ifdef DEBUG_UPROBES"; |