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Date: Mon, 16 May 2016 23:13:50 +0300
From: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
To: Rob Herring <robherring2@...il.com>
Cc: Frank Rowand <frowand.list@...il.com>,
Matt Porter <mporter@...sulko.com>,
Grant Likely <grant.likely@...retlab.ca>,
Koen Kooi <koen@...inion.thruhere.net>,
Guenter Roeck <linux@...ck-us.net>,
Marek Vasut <marex@...x.de>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/5] of: Support hashtable lookups for phandles
Hi Rob,
> On May 16, 2016, at 22:37 , Rob Herring <robherring2@...il.com> wrote:
>
> On Mon, May 16, 2016 at 11:52 AM, Pantelis Antoniou
> <pantelis.antoniou@...sulko.com> wrote:
>> When a device tree contains a lot of phandles, resolving one
>> takes time because the original method uses a search against
>> all nodes (not just the ones with phandles).
>>
>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
>> ---
>> drivers/of/base.c | 41 ++++++++++++++++++++++++++++++++++++++---
>> drivers/of/dynamic.c | 8 ++++++++
>> drivers/of/of_private.h | 33 +++++++++++++++++++++++++++++++++
>> include/linux/of.h | 2 ++
>> 4 files changed, 81 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>> index 20bbc2f..436a088 100644
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>> @@ -27,6 +27,7 @@
>> #include <linux/slab.h>
>> #include <linux/string.h>
>> #include <linux/proc_fs.h>
>> +#include <linux/rhashtable.h>
>>
>> #include "of_private.h"
>>
>> @@ -41,6 +42,18 @@ static const char *of_stdout_options;
>>
>> struct kset *of_kset;
>>
>> +const struct rhashtable_params of_phandle_ht_params = {
>
> static
>
No, it won’t work. The rhashtable API requires using this at every call.
>> + .key_offset = offsetof(struct device_node, phandle), /* base offset */
>> + .key_len = sizeof(phandle),
>> + .head_offset = offsetof(struct device_node, ht_node),
>> + .automatic_shrinking = true,
>> +};
>> +
>> +struct rhashtable *of_phandle_ht;
>> +
>> +/* default is false */
>> +bool of_phandle_ht_is_disabled;
>
> I think this should go. The unittest alone is not enough reason to keep.
>
Hmm, OK.
>> +
>> /*
>> * Used to protect the of_aliases, to hold off addition of nodes to sysfs.
>> * This mutex must be held whenever modifications are being made to the
>> @@ -162,6 +175,12 @@ int __of_attach_node_post(struct device_node *np)
>> struct property *pp;
>> int rc;
>>
>> + if (of_phandle_ht_available()) {
>
> This can never be false as this function should only get called after init.
>
How about a BUG_ON() just in case something weird is going on?
>> + rc = of_phandle_ht_insert(np);
>> + WARN(rc, "insert to phandle hash fail @%s\n",
>> + of_node_full_name(np));
>> + }
>> +
>> if (!IS_ENABLED(CONFIG_SYSFS))
>> return 0;
>>
>> @@ -194,6 +213,17 @@ void __init of_core_init(void)
>> struct device_node *np;
>> int ret;
>>
>> + of_phandle_ht = kzalloc(sizeof(*of_phandle_ht), GFP_KERNEL);
>> + if (!of_phandle_ht) {
>> + pr_warn("devicetree: Failed to allocate hashtable\n");
>> + return;
>> + }
>> + ret = rhashtable_init(of_phandle_ht, &of_phandle_ht_params);
>> + if (ret) {
>> + pr_warn("devicetree: Failed to initialize hashtable\n");
>> + return;
>> + }
>> +
>> /* Create the kset, and register existing nodes */
>> mutex_lock(&of_mutex);
>> of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
>> @@ -1073,9 +1103,14 @@ struct device_node *of_find_node_by_phandle(phandle handle)
>> return NULL;
>>
>> raw_spin_lock_irqsave(&devtree_lock, flags);
>> - for_each_of_allnodes(np)
>> - if (np->phandle == handle)
>> - break;
>> + /* when we're ready use the hash table (and not disabled) */
>> + if (of_phandle_ht_available() && !of_phandle_ht_is_disabled)
>
> Just "if (of_phandle_ht)”
>
OK
>> + np = of_phandle_ht_lookup(handle);
>> + else { /* fallback */
>> + for_each_of_allnodes(np)
>> + if (np->phandle == handle)
>> + break;
>> + }
>> of_node_get(np);
>> raw_spin_unlock_irqrestore(&devtree_lock, flags);
>> return np;
>> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
>> index 34ca783..931b905 100644
>> --- a/drivers/of/dynamic.c
>> +++ b/drivers/of/dynamic.c
>> @@ -11,6 +11,7 @@
>> #include <linux/slab.h>
>> #include <linux/string.h>
>> #include <linux/proc_fs.h>
>> +#include <linux/rhashtable.h>
>>
>> #include "of_private.h"
>>
>> @@ -44,6 +45,13 @@ EXPORT_SYMBOL(of_node_put);
>> void __of_detach_node_post(struct device_node *np)
>> {
>> struct property *pp;
>> + int rc;
>> +
>> + if (of_phandle_ht_available()) {
>
> Likewise, this can't be false either.
>
OK
>> + rc = of_phandle_ht_remove(np);
>> + WARN(rc, "remove from phandle hash fail @%s\n",
>> + of_node_full_name(np));
>> + }
>>
>> if (!IS_ENABLED(CONFIG_SYSFS))
>> return;
>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>> index 10b0342..386ae71 100644
>> --- a/drivers/of/of_private.h
>> +++ b/drivers/of/of_private.h
>> @@ -101,4 +101,37 @@ static inline int of_overlay_init(void)
>> }
>> #endif
>>
>> +extern const struct rhashtable_params of_phandle_ht_params;
>> +extern struct rhashtable *of_phandle_ht;
>> +
>> +/* for unittest use */
>> +extern bool of_phandle_ht_is_disabled;
>> +
>> +static inline bool of_phandle_ht_available(void)
>> +{
>> + return of_phandle_ht != NULL;
>> +}
>> +
>> +static inline int of_phandle_ht_insert(struct device_node *np)
>> +{
>> + if (!np || !np->phandle)
>> + return 0;
>> + return rhashtable_insert_fast(of_phandle_ht,
>> + &np->ht_node, of_phandle_ht_params);
>> +}
>> +
>> +static inline int of_phandle_ht_remove(struct device_node *np)
>> +{
>> + if (!np || !np->phandle)
>> + return 0;
>> + return rhashtable_remove_fast(of_phandle_ht,
>> + &np->ht_node, of_phandle_ht_params);
>> +}
>> +
>> +static inline struct device_node *of_phandle_ht_lookup(phandle handle)
>> +{
>> + return rhashtable_lookup_fast(of_phandle_ht,
>> + &handle, of_phandle_ht_params);
>> +}
>> +
>> #endif /* _LINUX_OF_PRIVATE_H */
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 18a8e59..9de9a3f 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -25,6 +25,7 @@
>> #include <linux/notifier.h>
>> #include <linux/property.h>
>> #include <linux/list.h>
>> +#include <linux/rhashtable.h>
>>
>> #include <asm/byteorder.h>
>> #include <asm/errno.h>
>> @@ -52,6 +53,7 @@ struct device_node {
>> phandle phandle;
>> const char *full_name;
>> struct fwnode_handle fwnode;
>> + struct rhash_head ht_node;
>
> Place next to .phandle as both will be accessed at the same time.
>
OK.
>>
>> struct property *properties;
>> struct property *deadprops; /* removed properties */
>> --
>> 1.7.12
Regards
— Pantelis
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