soc: qcom: smp2p: Add memory barrier for irq_pending (f2197a20) · Commits · e / devices / android_kernel_fairphone_FP5

There is a very tight race where the irq_retrigger function is run on one cpu and the actual retrigger softirq is running on a second cpu. When this happens, there may be a chance that the second cpu will not see the updated irq_pending value from first cpu. Add a memory barrier to ensure that irq_pending is read correctly. Change-Id: I3dd185decc4f050bd57c0b6558f417ead2a3aa5a Signed-off-by:

Chris Lew <clew@codeaurora.org>

drivers/soc/qcom/smp2p.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -270,6 +270,9 @@ static void qcom_smp2p_notify_in(struct qcom_smp2p *smp2p)

		status = val ^ entry->last_value;
		entry->last_value = val;

		/* Ensure irq_pending is read correctly */
		mb();
		status \|= *entry->irq_pending;

		SMP2P_INFO("%d:\t%s: status:%0lx val:%0x\n",
		@@ -391,6 +394,11 @@ static int smp2p_retrigger_irq(struct irq_data *irqd)
		SMP2P_INFO("%d: %s: %lu\n", entry->smp2p->remote_pid, entry->name, irq);
		set_bit(irq, entry->irq_pending);

		/* Ensure irq_pending is visible to all cpus that retried interrupt
		* can run on
		*/
		mb();

		return 0;
		}