From 2969c7df1c1808d2a38a9adfbb158de7632a0cfb Mon Sep 17 00:00:00 2001 From: Rafael J. Wysocki Date: Mon, 3 Nov 2008 19:01:03 +0900 Subject: [PATCH] DMI: Introduce dmi_first_match to make the interface more flexible References: bnc#441721 Some notebooks from HP have the problem that their BIOSes attempt to spin down hard drives before entering ACPI system states S4 and S5. This leads to a yo-yo effect during system power-off shutdown and the last phase of hibernation when the disk is first spun down by the kernel and then almost immediately turned on and off by the BIOS. This, in turn, may result in shortening the disk's life times. To prevent this from happening we can blacklist the affected systems using DMI information. However, only the on-board controlles should be blacklisted and their PCI slot numbers can be used for this purpose. Unfortunately the existing interface for checking DMI information of the system is not very convenient for this purpose, because to use it, we would have to define special callback functions or create a separate struct dmi_system_id table for each blacklisted system. To overcome this difficulty introduce a new function dmi_first_match() returning a pointer to the first entry in an array of struct dmi_system_id elements that matches the system DMI information. Then, we can use this pointer to access the entry's .driver_data field containing the additional information, such as the PCI slot number, allowing us to do the desired blacklisting. Signed-off-by: Rafael J. Wysocki Signed-off-by: Tejun Heo Signed-off-by: Jeff Garzik Signed-off-by: Tejun Heo --- drivers/firmware/dmi_scan.c | 68 +++++++++++++++++++++++++++++++++----------- include/linux/dmi.h | 3 + 2 files changed, 55 insertions(+), 16 deletions(-) --- a/drivers/firmware/dmi_scan.c +++ b/drivers/firmware/dmi_scan.c @@ -407,6 +407,27 @@ void __init dmi_scan_machine(void) } /** + * dmi_match - check if dmi_system_id structure matches system DMI data + * @dmi: pointer to the dmi_system_id structure to check + */ +static bool dmi_match(const struct dmi_system_id *dmi) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(dmi->matches); i++) { + int s = dmi->matches[i].slot; + if (s == DMI_NONE) + continue; + if (dmi_ident[s] + && strstr(dmi_ident[s], dmi->matches[i].substr)) + continue; + /* No match */ + return false; + } + return true; +} + +/** * 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 @@ -421,30 +442,45 @@ void __init dmi_scan_machine(void) */ int dmi_check_system(const struct dmi_system_id *list) { - int i, count = 0; - const struct dmi_system_id *d = list; + int count = 0; + const struct dmi_system_id *d; - while (d->ident) { - for (i = 0; i < ARRAY_SIZE(d->matches); i++) { - int s = d->matches[i].slot; - if (s == DMI_NONE) - continue; - if (dmi_ident[s] && strstr(dmi_ident[s], d->matches[i].substr)) - continue; - /* No match */ - goto fail; + for (d = list; d->ident; d++) + if (dmi_match(d)) { + count++; + if (d->callback && d->callback(d)) + break; } - count++; - if (d->callback && d->callback(d)) - break; -fail: d++; - } return count; } EXPORT_SYMBOL(dmi_check_system); /** + * dmi_first_match - find dmi_system_id structure matching system DMI data + * @list: array of dmi_system_id structures to match against + * All non-null elements of the list must match + * their slot's (field index's) data (i.e., each + * list string must be a substring of the specified + * DMI slot's string data) to be considered a + * successful match. + * + * Walk the blacklist table until the first match is found. Return the + * pointer to the matching entry or NULL if there's no match. + */ +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++) + if (dmi_match(d)) + return d; + + return NULL; +} +EXPORT_SYMBOL(dmi_first_match); + +/** * dmi_get_system_info - return DMI data value * @field: data index (see enum dmi_field) * --- a/include/linux/dmi.h +++ b/include/linux/dmi.h @@ -75,6 +75,7 @@ struct dmi_device { #ifdef CONFIG_DMI extern int dmi_check_system(const struct dmi_system_id *list); +const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list); extern const char * dmi_get_system_info(int field); extern const struct dmi_device * dmi_find_device(int type, const char *name, const struct dmi_device *from); @@ -88,6 +89,8 @@ extern int dmi_walk(void (*decode)(const #else static inline int dmi_check_system(const struct dmi_system_id *list) { return 0; } +static inline const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list) + { return NULL; } static inline const char * dmi_get_system_info(int field) { return NULL; } static inline const struct dmi_device * dmi_find_device(int type, const char *name, const struct dmi_device *from) { return NULL; }