linux-kernel - Re: [PATCH 7/8] cpumask: convert misc driver functions

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Date:	Mon, 29 Dec 2008 12:58:35 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	Mike Travis <travis@....com>, Ingo Molnar <mingo@...hat.com>,
	linux-kernel@...r.kernel.org, Dean Nelson <dcn@....com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Robert Richter <robert.richter@....com>
Subject: Re: [PATCH 7/8] cpumask: convert misc driver functions

On Sunday 21 December 2008 09:52:39 Ben Hutchings wrote:
> I assume you're moving the allocation up to efx_probe_nic() because
> efx_wanted_rx_queues() and efx_probe_interrupts() cannot return failure.
> It really isn't worth exposing that detail up the call chain though.  I
> think it's acceptable for efx_wanted_rx_queues() to log an error message
> and return 1 in the exceedingly unlikely case that the allocation fails.

OK, fair call.  I was trying trying hard not to break anything.

How's this?

cpumask: convert drivers/net/sfc

Remove a cpumask from the stack.  Ben Hutchings indicated that printing
a warning and returning 1 was acceptable for the corner case where allocation
fails.

Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Cc: Ben Hutchings <bhutchings@...arflare.com>

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -854,20 +854,27 @@ static void efx_fini_io(struct efx_nic *
  * interrupts across them. */
 static int efx_wanted_rx_queues(void)
 {
-	cpumask_t core_mask;
+	cpumask_var_t core_mask;
 	int count;
 	int cpu;
 
-	cpus_clear(core_mask);
+	if (!alloc_cpumask_var(&core_mask, GFP_KERNEL)) {
+		printk(KERN_WARNING
+		       "efx.c: allocation failure, irq balancing hobbled\n");
+		return 1;
+	}
+
+	cpumask_clear(core_mask);
 	count = 0;
 	for_each_online_cpu(cpu) {
-		if (!cpu_isset(cpu, core_mask)) {
+		if (!cpumask_test_cpu(cpu, core_mask)) {
 			++count;
-			cpumask_or(&core_mask, &core_mask,
+			cpumask_or(core_mask, core_mask,
 				   topology_core_cpumask(cpu));
 		}
 	}
 
+	free_cpumask_var(core_mask);
 	return count;
 }
 
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