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SubjectRe: [PATCH] DMI: allow omitting ident strings in DMI tables
On Thu, Dec 03, 2009 at 10:25:42AM +0100, Jean Delvare wrote:
> On Thu, 3 Dec 2009 00:56:30 -0800, Dmitry Torokhov wrote:
> > On Thu, Dec 03, 2009 at 09:30:09AM +0100, Jean Delvare wrote:
> > > On Wed, 2 Dec 2009 19:12:40 -0800, Dmitry Torokhov wrote:
> > > > diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> > > > index 938100f..9116aa7 100644
> > > > --- a/drivers/firmware/dmi_scan.c
> > > > +++ b/drivers/firmware/dmi_scan.c
> > > > @@ -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->ident == NULL && dmi->matches[0].slot == DMI_NONE;
> > >
> > > If you really want to allow for dmi->ident == NULL, then I guess you can
> > > _only_ check for dmi->matches[0].slot == DMI_NONE. I can't think of any
> > > legitimate use of DMI_NONE for a used slot.
> >
> > Current behavior is that entry with ident and empty match table matches
> > everything. If we only check on the first slot then it will not match. I
> > wanted to preserve the current behavior.
>
> Is there a use case for this behavior? If not then I don't see the
> point of preserving it.
>

I looked through current uses of dmi_check_system and could not find
any cases where anyone would rely on this behavior. Thus the updated
patch below.

Thanks.

--
Dmitry


DMI: allow omitting ident strings in DMI tables

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

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 enties with empty first match slot serve as
end-of-table markers instead.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
drivers/firmware/dmi_scan.c | 15 ++++++++++++---
1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 938100f..3a2ccb0 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;


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