DMI: allow omitting ident strings in DMI tables

The purpose of dmi->ident is twofold - it may be used by DMI callback
functions when composing log messages; it is also used to determine
end of DMI table in dmi_check_system() and dmi_first_match(). However,
in case when callbacks are not interested in using ident at all it just
wastes memory. Let's make entries with empty first match slot serve as
end-of-table markers instead.

Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 12 insertions, 3 deletions

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 938100f14b1..3a2ccb09e2f 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -429,7 +429,7 @@ static bool dmi_matches(const struct dmi_system_id *dmi)
         for (i = 0; i < ARRAY_SIZE(dmi->matches); i++) {
                 int s = dmi->matches[i].slot;
                 if (s == DMI_NONE)
-                        continue;
+                        break;
                 if (dmi_ident[s]
                     && strstr(dmi_ident[s], dmi->matches[i].substr))
                         continue;
@@ -440,6 +440,15 @@ static bool dmi_matches(const struct dmi_system_id *dmi)
 }
 
 /**
+ *      dmi_is_end_of_table - check for end-of-table marker
+ *      @dmi: pointer to the dmi_system_id structure to check
+ */
+static bool dmi_is_end_of_table(const struct dmi_system_id *dmi)
+{
+        return dmi->matches[0].slot == DMI_NONE;
+}
+
+/**
  *      dmi_check_system - check system DMI data
  *      @list: array of dmi_system_id structures to match against
  *              All non-null elements of the list must match
@@ -457,7 +466,7 @@ int dmi_check_system(const struct dmi_system_id *list)
         int count = 0;
         const struct dmi_system_id *d;
 
-        for (d = list; d->ident; d++)
+        for (d = list; !dmi_is_end_of_table(d); d++)
                 if (dmi_matches(d)) {
                         count++;
                         if (d->callback && d->callback(d))
@@ -484,7 +493,7 @@ const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list)
 {
         const struct dmi_system_id *d;
 
-        for (d = list; d->ident; d++)
+        for (d = list; !dmi_is_end_of_table(d); d++)
                 if (dmi_matches(d))
                         return d;