dmi scan: warn about too early calls to dmi_check_system()

It happened to me recently that i added a dmi_check_system() quirk
in a too early codepath, and it was silently ignored because all the
DMI tables and strings were still empty.

As this situation is clearly a programming error / kernel bug,
warn when it happens, instead of silently ignoring quirks.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 16 insertions, 6 deletions

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 455575be3560..3e526b6d00cb 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -15,6 +15,11 @@
  */
 static char dmi_empty_string[] = "        ";
 
+/*
+ * Catch too early calls to dmi_check_system():
+ */
+static int dmi_initialized;
+
 static const char * __init dmi_string_nosave(const struct dmi_header *dm, u8 s)
 {
         const u8 *bp = ((u8 *) dm) + dm->length;
@@ -366,7 +371,7 @@ void __init dmi_scan_machine(void)
 
         if (efi_enabled) {
                 if (efi.smbios == EFI_INVALID_TABLE_ADDR)
-                        goto out;
+                        goto error;
 
                 /* This is called as a core_initcall() because it isn't
                  * needed during early boot.  This also means we can
@@ -374,13 +379,13 @@ void __init dmi_scan_machine(void)
                  */
                 p = dmi_ioremap(efi.smbios, 32);
                 if (p == NULL)
-                        goto out;
+                        goto error;
 
                 rc = dmi_present(p + 0x10); /* offset of _DMI_ string */
                 dmi_iounmap(p, 32);
                 if (!rc) {
                         dmi_available = 1;
-                        return;
+                        goto out;
                 }
         }
         else {
@@ -391,19 +396,22 @@ void __init dmi_scan_machine(void)
                  */
                 p = dmi_ioremap(0xF0000, 0x10000);
                 if (p == NULL)
-                        goto out;
+                        goto error;
 
                 for (q = p; q < p + 0x10000; q += 16) {
                         rc = dmi_present(q);
                         if (!rc) {
                                 dmi_available = 1;
                                 dmi_iounmap(p, 0x10000);
-                                return;
+                                goto out;
                         }
                 }
                 dmi_iounmap(p, 0x10000);
         }
- out:   printk(KERN_INFO "DMI not present or invalid.\n");
+ error:
+        printk(KERN_INFO "DMI not present or invalid.\n");
+ out:
+        dmi_initialized = 1;
 }
 
 /**
@@ -424,6 +432,8 @@ int dmi_check_system(const struct dmi_system_id *list)
         int i, count = 0;
         const struct dmi_system_id *d = list;
 
+        WARN(!dmi_initialized, KERN_ERR "dmi check: not initialized yet.\n");
+
         while (d->ident) {
                 for (i = 0; i < ARRAY_SIZE(d->matches); i++) {
                         int s = d->matches[i].slot;