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Subject[PATCH] firmware: dmi_scan: Drop dmi_initialized
I don't think it makes sense to check for a possible bad
initialization order at run time on every system when it is all
decided at build time.

A more efficient way to make sure developers do not introduce new
calls to dmi_check_system() too early in the initialization sequence
is to simply document the expected call order. That way, developers
have a chance to get it right immediately, without having to
test-boot their kernel, wonder why it does not work, and parse the
kernel logs for a warning message. And we get rid of the run-time
performance penalty as a nice side effect.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Ingo Molnar <mingo@kernel.org>
---
drivers/firmware/dmi_scan.c | 21 ++++++++-------------
1 file changed, 8 insertions(+), 13 deletions(-)

--- linux-4.14-rc0.orig/drivers/firmware/dmi_scan.c 2017-09-15 11:58:10.005977920 +0200
+++ linux-4.14-rc0/drivers/firmware/dmi_scan.c 2017-09-18 09:00:01.506399879 +0200
@@ -26,11 +26,6 @@ static u16 dmi_num;
static u8 smbios_entry_point[32];
static int smbios_entry_point_size;

-/*
- * Catch too early calls to dmi_check_system():
- */
-static int dmi_initialized;
-
/* DMI system identification string used during boot */
static char dmi_ids_string[128] __initdata;

@@ -633,7 +628,7 @@ void __init dmi_scan_machine(void)

if (!dmi_smbios3_present(buf)) {
dmi_available = 1;
- goto out;
+ return;
}
}
if (efi.smbios == EFI_INVALID_TABLE_ADDR)
@@ -651,7 +646,7 @@ void __init dmi_scan_machine(void)

if (!dmi_present(buf)) {
dmi_available = 1;
- goto out;
+ return;
}
} else if (IS_ENABLED(CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK)) {
p = dmi_early_remap(0xF0000, 0x10000);
@@ -668,7 +663,7 @@ void __init dmi_scan_machine(void)
if (!dmi_smbios3_present(buf)) {
dmi_available = 1;
dmi_early_unmap(p, 0x10000);
- goto out;
+ return;
}
memcpy(buf, buf + 16, 16);
}
@@ -686,7 +681,7 @@ void __init dmi_scan_machine(void)
if (!dmi_present(buf)) {
dmi_available = 1;
dmi_early_unmap(p, 0x10000);
- goto out;
+ return;
}
memcpy(buf, buf + 16, 16);
}
@@ -694,8 +689,6 @@ void __init dmi_scan_machine(void)
}
error:
pr_info("DMI not present or invalid.\n");
- out:
- dmi_initialized = 1;
}

static ssize_t raw_table_read(struct file *file, struct kobject *kobj,
@@ -827,14 +820,14 @@ static bool dmi_is_end_of_table(const st
* Walk the blacklist table running matching functions until someone
* returns non zero or we hit the end. Callback function is called for
* each successful match. Returns the number of matches.
+ *
+ * dmi_scan_machine must be called before this function is called.
*/
int dmi_check_system(const struct dmi_system_id *list)
{
int count = 0;
const struct dmi_system_id *d;

- WARN(!dmi_initialized, KERN_ERR "dmi check: not initialized yet.\n");
-
for (d = list; !dmi_is_end_of_table(d); d++)
if (dmi_matches(d)) {
count++;
@@ -857,6 +850,8 @@ EXPORT_SYMBOL(dmi_check_system);
*
* Walk the blacklist table until the first match is found. Return the
* pointer to the matching entry or NULL if there's no match.
+ *
+ * dmi_scan_machine must be called before this function is called.
*/
const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list)
{

--
Jean Delvare
SUSE L3 Support

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