On Studio 1555 with dual-core CPU, reading sensor attributes exported by this driver resulted in random failures combined with system hangups and forced logouts. Information in drivers/firmware/dcdbas.c suggests that SMM accesses must run on CPU 0. With this patch, the problems are gone, suggesting that this is in fact the case.
Code derived from drivers/firmware/dcdbas.c. Cc: Jean Delvare <[email protected]> Signed-off-by: Guenter Roeck <[email protected]> --- drivers/char/i8k.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c index ad0acef..264be2b 100644 --- a/drivers/char/i8k.c +++ b/drivers/char/i8k.c @@ -31,6 +31,7 @@ #include <linux/hwmon-sysfs.h> #include <linux/uaccess.h> #include <linux/io.h> +#include <linux/sched.h> #include <linux/i8k.h> @@ -130,6 +131,17 @@ 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); + set_cpus_allowed_ptr(current, cpumask_of(0)); + if (smp_processor_id() != 0) { + rc = -EBUSY; + goto out; + } #if defined(CONFIG_X86_64) asm volatile("pushq %%rax\n\t" @@ -185,9 +197,12 @@ static int i8k_smm(struct smm_regs *regs) : "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"); #endif if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax) - return -EINVAL; + rc = -EINVAL; - return 0; +out: + set_cpus_allowed_ptr(current, old_mask); + free_cpumask_var(old_mask); + return rc; } /* -- 1.7.9.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
