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Commit bb929284 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Kill UPROBE_RUN_HANDLER flag 



Simply remove UPROBE_RUN_HANDLER and the corresponding code.

It can only help if uprobe has a single consumer, and in fact
it is no longer needed after handler_chain() was changed to use
->register_rwsem, we simply can not race with uprobe_register().

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent 1ff6fee5

kernel/events/uprobes.c

+5 −18
Original line number Diff line number Diff line
@@ -83,10 +83,8 @@ static atomic_t uprobe_events = ATOMIC_INIT(0); 


/* Have a copy of original instruction */

#define UPROBE_COPY_INSN	0

/* Dont run handlers when first register/ last unregister in progress*/

#define UPROBE_RUN_HANDLER	1

/* Can skip singlestep */

#define UPROBE_SKIP_SSTEP	2

#define UPROBE_SKIP_SSTEP	1



struct uprobe {

	struct rb_node		rb_node;	/* node in the rb tree */
@@ -475,9 +473,6 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 
{

	struct uprobe_consumer *uc;



	if (!test_bit(UPROBE_RUN_HANDLER, &uprobe->flags))

		return;



	down_read(&uprobe->register_rwsem);

	for (uc = uprobe->consumers; uc; uc = uc->next)

		uc->handler(uc, regs);
@@ -825,13 +820,8 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 


static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)

{

	int err;



	consumer_add(uprobe, uc);

	err = register_for_each_vma(uprobe, true);

	if (!err) /* TODO: pointless unless the first consumer */

		set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);

	return err;

	return register_for_each_vma(uprobe, true);

}



static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
@@ -842,13 +832,10 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u 
		return;



	err = register_for_each_vma(uprobe, false);

	if (!uprobe->consumers) {

		clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags);

	/* TODO : cant unregister? schedule a worker thread */

		if (!err)

	if (!uprobe->consumers && !err)

		delete_uprobe(uprobe);

}

}



/*

 * uprobe_register - register a probe