x86: cpuid: propagate error from smp_call_function_single()

Propagate error (-ENXIO) from smp_call_function_single() in the CPUID
driver.  This can happen when a CPU is unplugged while the CPUID
driver is open.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index 14b11b3..23e8316 100644 (file)
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -89,6 +89,7 @@ static ssize_t cpuid_read(struct file *file, char __user *buf,
        struct cpuid_regs cmd;
        int cpu = iminor(file->f_path.dentry->d_inode);
        u64 pos = *ppos;
+       int err;
 
        if (count % 16)
                return -EINVAL; /* Invalid chunk size */
@@ -96,7 +97,9 @@ static ssize_t cpuid_read(struct file *file, char __user *buf,
        for (; count; count -= 16) {
                cmd.eax = pos;
                cmd.ecx = pos >> 32;
-               smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1);
+               err = smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1);
+               if (err)
+                       return err;
                if (copy_to_user(tmp, &cmd, 16))
                        return -EFAULT;
                tmp += 16;