| Message ID | 1353453142-4973-1-git-send-email-swarren@wwwdotorg.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/20/2012 05:12 PM, Stephen Warren wrote: > From: Stephen Warren <swarren@nvidia.com> > > The following pattern of code is tempting: > > for_each_matching_node(np, table) { > match = of_match_node(table, np); > > However, this results in iterating over table twice; the second time > inside of_match_node(). The implementation of for_each_matching_node() > already found the match, so this is redundant. Invent new function > of_find_matching_node_and_match() and macro > for_each_matching_node_and_match() to remove the double iteration, > thus transforming the above code to: > > for_each_matching_node_and_match(np, table, &match) > > Signed-off-by: Stephen Warren <swarren@nvidia.com> > --- > v4: New patch. > > This series is based on the ARM sys_timer rework that I posted yesterday, > although patch 1/3 should be completely independant of that, and could > perhaps even be applied for 3.8 right now. Agreed. I will apply for 3.8 assuming no further comments in the next few days. Rob > I hope that these patches can be taken through arm-soc tree for 3.9; > I will repost them based on 3.8-rc1 at the appropriate time. > --- > drivers/of/base.c | 18 +++++++++++++----- > include/linux/of.h | 15 +++++++++++++-- > 2 files changed, 26 insertions(+), 7 deletions(-) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index f2f63c8..094271e 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -594,27 +594,35 @@ const struct of_device_id *of_match_node(const struct of_device_id *matches, > EXPORT_SYMBOL(of_match_node); > > /** > - * of_find_matching_node - Find a node based on an of_device_id match > - * table. > + * of_find_matching_node_and_match - Find a node based on an of_device_id > + * match table. > * @from: The node to start searching from or NULL, the node > * you pass will not be searched, only the next one > * will; typically, you pass what the previous call > * returned. of_node_put() will be called on it > * @matches: array of of device match structures to search in > + * @match Updated to point at the matches entry which matched > * > * Returns a node pointer with refcount incremented, use > * of_node_put() on it when done. > */ > -struct device_node *of_find_matching_node(struct device_node *from, > - const struct of_device_id *matches) > +struct device_node *of_find_matching_node_and_match(struct device_node *from, > + const struct of_device_id *matches, > + const struct of_device_id **match) > { > struct device_node *np; > > + if (match) > + *match = NULL; > + > read_lock(&devtree_lock); > np = from ? from->allnext : allnodes; > for (; np; np = np->allnext) { > - if (of_match_node(matches, np) && of_node_get(np)) > + if (of_match_node(matches, np) && of_node_get(np)) { > + if (match) > + *match = matches; > break; > + } > } > of_node_put(from); > read_unlock(&devtree_lock); > diff --git a/include/linux/of.h b/include/linux/of.h > index 681a6c8..1000496 100644 > --- a/include/linux/of.h > +++ b/include/linux/of.h > @@ -180,11 +180,22 @@ extern struct device_node *of_find_compatible_node(struct device_node *from, > #define for_each_compatible_node(dn, type, compatible) \ > for (dn = of_find_compatible_node(NULL, type, compatible); dn; \ > dn = of_find_compatible_node(dn, type, compatible)) > -extern struct device_node *of_find_matching_node(struct device_node *from, > - const struct of_device_id *matches); > +extern struct device_node *of_find_matching_node_and_match( > + struct device_node *from, > + const struct of_device_id *matches, > + const struct of_device_id **match); > +static inline struct device_node *of_find_matching_node( > + struct device_node *from, > + const struct of_device_id *matches) > +{ > + return of_find_matching_node_and_match(from, matches, NULL); > +} > #define for_each_matching_node(dn, matches) \ > for (dn = of_find_matching_node(NULL, matches); dn; \ > dn = of_find_matching_node(dn, matches)) > +#define for_each_matching_node_and_match(dn, matches, match) \ > + for (dn = of_find_matching_node_and_match(NULL, matches, match); \ > + dn; dn = of_find_matching_node_and_match(dn, matches, match)) > extern struct device_node *of_find_node_by_path(const char *path); > extern struct device_node *of_find_node_by_phandle(phandle handle); > extern struct device_node *of_get_parent(const struct device_node *node); >
On Tuesday 20 November 2012, Stephen Warren wrote: > However, this results in iterating over table twice; the second time > inside of_match_node(). The implementation of for_each_matching_node() > already found the match, so this is redundant. Invent new function > of_find_matching_node_and_match() and macro > for_each_matching_node_and_match() to remove the double iteration, > thus transforming the above code to: > > for_each_matching_node_and_match(np, table, &match) > > Signed-off-by: Stephen Warren <swarren@nvidia.com> This look useful, but I wonder if the interface would make more sense if you make the last argument to the macro a normal pointer, rather than a pointer-to-pointer. You can take the reference as part of the macro. Arnd
On Wed, Nov 21, 2012 at 9:53 AM, Arnd Bergmann <arnd@arndb.de> wrote: > On Tuesday 20 November 2012, Stephen Warren wrote: >> However, this results in iterating over table twice; the second time >> inside of_match_node(). The implementation of for_each_matching_node() >> already found the match, so this is redundant. Invent new function >> of_find_matching_node_and_match() and macro >> for_each_matching_node_and_match() to remove the double iteration, >> thus transforming the above code to: >> >> for_each_matching_node_and_match(np, table, &match) >> >> Signed-off-by: Stephen Warren <swarren@nvidia.com> > > This look useful, but I wonder if the interface would make more sense if you > make the last argument to the macro a normal pointer, rather than a > pointer-to-pointer. You can take the reference as part of the macro. To me that makes for harder to understand code. It *looks* like an argument to a normal function call, but it gets changed by the caller. g.
On Wed, 21 Nov 2012 10:06:16 +0000, Grant Likely wrote: > On Wed, Nov 21, 2012 at 9:53 AM, Arnd Bergmann <arnd@arndb.de> wrote: > > On Tuesday 20 November 2012, Stephen Warren wrote: > >> However, this results in iterating over table twice; the second time > >> inside of_match_node(). The implementation of for_each_matching_node() > >> already found the match, so this is redundant. Invent new function > >> of_find_matching_node_and_match() and macro > >> for_each_matching_node_and_match() to remove the double iteration, > >> thus transforming the above code to: > >> > >> for_each_matching_node_and_match(np, table, &match) > >> > >> Signed-off-by: Stephen Warren <swarren@nvidia.com> > > > > This look useful, but I wonder if the interface would make more sense if you > > make the last argument to the macro a normal pointer, rather than a > > pointer-to-pointer. You can take the reference as part of the macro. > > To me that makes for harder to understand code. It *looks* like an > argument to a normal function call, but it gets changed by the caller. Agreed. Too much magic is too much. Thomas
diff --git a/drivers/of/base.c b/drivers/of/base.c index f2f63c8..094271e 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -594,27 +594,35 @@ const struct of_device_id *of_match_node(const struct of_device_id *matches, EXPORT_SYMBOL(of_match_node); /** - * of_find_matching_node - Find a node based on an of_device_id match - * table. + * of_find_matching_node_and_match - Find a node based on an of_device_id + * match table. * @from: The node to start searching from or NULL, the node * you pass will not be searched, only the next one * will; typically, you pass what the previous call * returned. of_node_put() will be called on it * @matches: array of of device match structures to search in + * @match Updated to point at the matches entry which matched * * Returns a node pointer with refcount incremented, use * of_node_put() on it when done. */ -struct device_node *of_find_matching_node(struct device_node *from, - const struct of_device_id *matches) +struct device_node *of_find_matching_node_and_match(struct device_node *from, + const struct of_device_id *matches, + const struct of_device_id **match) { struct device_node *np; + if (match) + *match = NULL; + read_lock(&devtree_lock); np = from ? from->allnext : allnodes; for (; np; np = np->allnext) { - if (of_match_node(matches, np) && of_node_get(np)) + if (of_match_node(matches, np) && of_node_get(np)) { + if (match) + *match = matches; break; + } } of_node_put(from); read_unlock(&devtree_lock); diff --git a/include/linux/of.h b/include/linux/of.h index 681a6c8..1000496 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -180,11 +180,22 @@ extern struct device_node *of_find_compatible_node(struct device_node *from, #define for_each_compatible_node(dn, type, compatible) \ for (dn = of_find_compatible_node(NULL, type, compatible); dn; \ dn = of_find_compatible_node(dn, type, compatible)) -extern struct device_node *of_find_matching_node(struct device_node *from, - const struct of_device_id *matches); +extern struct device_node *of_find_matching_node_and_match( + struct device_node *from, + const struct of_device_id *matches, + const struct of_device_id **match); +static inline struct device_node *of_find_matching_node( + struct device_node *from, + const struct of_device_id *matches) +{ + return of_find_matching_node_and_match(from, matches, NULL); +} #define for_each_matching_node(dn, matches) \ for (dn = of_find_matching_node(NULL, matches); dn; \ dn = of_find_matching_node(dn, matches)) +#define for_each_matching_node_and_match(dn, matches, match) \ + for (dn = of_find_matching_node_and_match(NULL, matches, match); \ + dn; dn = of_find_matching_node_and_match(dn, matches, match)) extern struct device_node *of_find_node_by_path(const char *path); extern struct device_node *of_find_node_by_phandle(phandle handle); extern struct device_node *of_get_parent(const struct device_node *node);