As a followup to this discussion:
On Tue, 15 Jul 2014 08:01:13 PM Sam Asadi wrote:
> Commit f36fdb9f0266 (i8k: Force SMM to run on CPU 0) adds support
> for multi-core CPUs to the driver. Unfortunately, that causes it
> to fail loading if compiled without SMP support, at least on
> 32 bit kernels. Kernel log shows "i8k: unable to get SMM Dell
> signature", and function i8k_smm is found to return -EINVAL.
>
> Testing revealed that the culprit is the missing return value check
> of set_cpus_allowed_ptr.
It appears that the original commit f36fdb9f0266 changes the affinity for the
duration of i8k_smm function and then unconditionally reverts the affinity to
the old cpu mask regardless of whether the function succeeds or fails. As this
must run on CPU 0 at all times it does not make sense to revert the affinity at
the end of the function. Proposed patch attached.
Signed-off-by: Con Kolivas <kernel@xxxxxxxxxxx>
---
drivers/char/i8k.c | 6 ------
1 file changed, 6 deletions(-)
Index: linux-3.16-ck1/drivers/char/i8k.c
===================================================================
--- linux-3.16-ck1.orig/drivers/char/i8k.c 2014-08-12 14:07:49.000000000 +1000
+++ linux-3.16-ck1/drivers/char/i8k.c 2014-08-19 09:09:57.939056696 +1000
@@ -132,12 +132,8 @@ static int i8k_smm(struct smm_regs *regs
{
int rc;
int eax = regs->eax;
- cpumask_var_t old_mask;
/* SMM requires CPU 0 */
- if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
- return -ENOMEM;
- cpumask_copy(old_mask, ¤t->cpus_allowed);
rc = set_cpus_allowed_ptr(current, cpumask_of(0));
if (rc)
goto out;
@@ -203,8 +199,6 @@ static int i8k_smm(struct smm_regs *regs
rc = -EINVAL;
out:
- set_cpus_allowed_ptr(current, old_mask);
- free_cpumask_var(old_mask);
return rc;
}
--
-ck
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