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>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index 14b11b3be31c..23e8316c8357 100644
--- 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;