On 03/22, Anton Arapov wrote:
>
> @@ -1488,10 +1496,14 @@ static void handler_chain(struct uprobe *uprobe,
> struct pt_regs *regs)
> {
> struct uprobe_consumer *uc;
> int remove = UPROBE_HANDLER_REMOVE;
> + int rc = 0;
>
> down_read(&uprobe->register_rwsem);
> for (uc = uprobe->consumers; uc; uc = uc->next) {
> - int rc = uc->handler(uc, regs);
> + if (uc->handler)
> + rc = uc->handler(uc, regs);
> + else
> + remove = 0;
Well, this doesn't look good. Yes, we need to conditionalize uc->handler()
and rc checks, but the code looks ugly. We touch remove twice, and the value
of rc inside the loop is bogus if ->handler == NULL.
I wouldn't have argued, but, but 4/7 changes the "else" branch and this change
is wrong (I'll write another email). We do not need this "else" at all.
I'd suggest the patch below.
Oleg.
--- x/kernel/events/uprobes.c
+++ x/kernel/events/uprobes.c
@@ -1491,10 +1491,13 @@ static void handler_chain(struct uprobe
down_read(&uprobe->register_rwsem);
for (uc = uprobe->consumers; uc; uc = uc->next) {
- int rc = uc->handler(uc, regs);
+ int rc = 0;
- WARN(rc & ~UPROBE_HANDLER_MASK,
- "bad rc=0x%x from %pf()\n", rc, uc->handler);
+ if (uc->handler) {
+ rc = uc->handler(uc, regs);
+ WARN(rc & ~UPROBE_HANDLER_MASK,
+ "bad rc=0x%x from %pf()\n", rc, uc->handler);
+ }
remove &= rc;
}
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