Messages in this thread Patch in this message | | | Date | Sat, 23 Mar 2013 18:42:23 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 1/7] uretprobes: preparation patch |
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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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