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Date: Fri, 08 Feb 2013 17:09:29 -0600
From: Rob Herring <robherring2@...il.com>
To: Paul Gortmaker <paul.gortmaker@...driver.com>
CC: Grant Likely <grant.likely@...retlab.ca>,
Sam Ravnborg <sam@...nborg.org>,
devicetree-discuss@...ts.ozlabs.org, sparclinux@...r.kernel.org,
linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH next v2] OF: convert devtree lock from rw_lock to raw
spinlock
On 02/06/2013 02:30 PM, Paul Gortmaker wrote:
> From: Thomas Gleixner <tglx@...utronix.de>
>
> With the locking cleanup in place (from "OF: Fixup resursive
> locking code paths"), we can now do the conversion from the
> rw_lock to a raw spinlock as required for preempt-rt.
>
> The previous cleanup and this conversion were originally
> separate since they predated when mainline got raw spinlock (in
> commit c2f21ce2e31286a "locking: Implement new raw_spinlock").
>
> So, at that point in time, the cleanup was considered plausible
> for mainline, but not this conversion. In any case, we've kept
> them separate as it makes for easier review and better bisection.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> [PG: taken from preempt-rt, update subject & add a commit log]
> Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
> ---
>
> [v2: recent commit e81b329 ("powerpc+of: Add /proc device tree
> updating to of node add/remove") added two more instances of
> write_unlock that also needed converting to raw_spin_unlock.
> Retested (boot) on sbc8548, defconfig builds on arm/sparc; no
> new warnings observed.]
>
> arch/sparc/kernel/prom_common.c | 4 +-
> drivers/of/base.c | 100 ++++++++++++++++++++++------------------
> include/linux/of.h | 2 +-
> 3 files changed, 59 insertions(+), 47 deletions(-)
Applied.
Rob
>
> diff --git a/arch/sparc/kernel/prom_common.c b/arch/sparc/kernel/prom_common.c
> index 1303021..9f20566 100644
> --- a/arch/sparc/kernel/prom_common.c
> +++ b/arch/sparc/kernel/prom_common.c
> @@ -64,7 +64,7 @@ int of_set_property(struct device_node *dp, const char *name, void *val, int len
> err = -ENODEV;
>
> mutex_lock(&of_set_property_mutex);
> - write_lock(&devtree_lock);
> + raw_spin_lock(&devtree_lock);
> prevp = &dp->properties;
> while (*prevp) {
> struct property *prop = *prevp;
> @@ -91,7 +91,7 @@ int of_set_property(struct device_node *dp, const char *name, void *val, int len
> }
> prevp = &(*prevp)->next;
> }
> - write_unlock(&devtree_lock);
> + raw_spin_unlock(&devtree_lock);
> mutex_unlock(&of_set_property_mutex);
>
> /* XXX Upate procfs if necessary... */
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 16ee7a0..f86be55 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -55,7 +55,7 @@ static DEFINE_MUTEX(of_aliases_mutex);
> /* use when traversing tree through the allnext, child, sibling,
> * or parent members of struct device_node.
> */
> -DEFINE_RWLOCK(devtree_lock);
> +DEFINE_RAW_SPINLOCK(devtree_lock);
>
> int of_n_addr_cells(struct device_node *np)
> {
> @@ -188,10 +188,11 @@ struct property *of_find_property(const struct device_node *np,
> int *lenp)
> {
> struct property *pp;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> pp = __of_find_property(np, name, lenp);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
> return pp;
> }
> @@ -209,13 +210,13 @@ struct device_node *of_find_all_nodes(struct device_node *prev)
> {
> struct device_node *np;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock(&devtree_lock);
> np = prev ? prev->allnext : of_allnodes;
> for (; np != NULL; np = np->allnext)
> if (of_node_get(np))
> break;
> of_node_put(prev);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock(&devtree_lock);
> return np;
> }
> EXPORT_SYMBOL(of_find_all_nodes);
> @@ -274,11 +275,12 @@ static int __of_device_is_compatible(const struct device_node *device,
> int of_device_is_compatible(const struct device_node *device,
> const char *compat)
> {
> + unsigned long flags;
> int res;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> res = __of_device_is_compatible(device, compat);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return res;
> }
> EXPORT_SYMBOL(of_device_is_compatible);
> @@ -340,13 +342,14 @@ EXPORT_SYMBOL(of_device_is_available);
> struct device_node *of_get_parent(const struct device_node *node)
> {
> struct device_node *np;
> + unsigned long flags;
>
> if (!node)
> return NULL;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> np = of_node_get(node->parent);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> }
> EXPORT_SYMBOL(of_get_parent);
> @@ -365,14 +368,15 @@ EXPORT_SYMBOL(of_get_parent);
> struct device_node *of_get_next_parent(struct device_node *node)
> {
> struct device_node *parent;
> + unsigned long flags;
>
> if (!node)
> return NULL;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> parent = of_node_get(node->parent);
> of_node_put(node);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return parent;
> }
>
> @@ -388,14 +392,15 @@ struct device_node *of_get_next_child(const struct device_node *node,
> struct device_node *prev)
> {
> struct device_node *next;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> next = prev ? prev->sibling : node->child;
> for (; next; next = next->sibling)
> if (of_node_get(next))
> break;
> of_node_put(prev);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return next;
> }
> EXPORT_SYMBOL(of_get_next_child);
> @@ -413,7 +418,7 @@ struct device_node *of_get_next_available_child(const struct device_node *node,
> {
> struct device_node *next;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock(&devtree_lock);
> next = prev ? prev->sibling : node->child;
> for (; next; next = next->sibling) {
> if (!of_device_is_available(next))
> @@ -422,7 +427,7 @@ struct device_node *of_get_next_available_child(const struct device_node *node,
> break;
> }
> of_node_put(prev);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock(&devtree_lock);
> return next;
> }
> EXPORT_SYMBOL(of_get_next_available_child);
> @@ -460,14 +465,15 @@ EXPORT_SYMBOL(of_get_child_by_name);
> struct device_node *of_find_node_by_path(const char *path)
> {
> struct device_node *np = of_allnodes;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> for (; np; np = np->allnext) {
> if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
> && of_node_get(np))
> break;
> }
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> }
> EXPORT_SYMBOL(of_find_node_by_path);
> @@ -487,15 +493,16 @@ struct device_node *of_find_node_by_name(struct device_node *from,
> const char *name)
> {
> struct device_node *np;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> np = from ? from->allnext : of_allnodes;
> for (; np; np = np->allnext)
> if (np->name && (of_node_cmp(np->name, name) == 0)
> && of_node_get(np))
> break;
> of_node_put(from);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> }
> EXPORT_SYMBOL(of_find_node_by_name);
> @@ -516,15 +523,16 @@ struct device_node *of_find_node_by_type(struct device_node *from,
> const char *type)
> {
> struct device_node *np;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> np = from ? from->allnext : of_allnodes;
> for (; np; np = np->allnext)
> if (np->type && (of_node_cmp(np->type, type) == 0)
> && of_node_get(np))
> break;
> of_node_put(from);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> }
> EXPORT_SYMBOL(of_find_node_by_type);
> @@ -547,8 +555,9 @@ struct device_node *of_find_compatible_node(struct device_node *from,
> const char *type, const char *compatible)
> {
> struct device_node *np;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> np = from ? from->allnext : of_allnodes;
> for (; np; np = np->allnext) {
> if (type
> @@ -559,7 +568,7 @@ struct device_node *of_find_compatible_node(struct device_node *from,
> break;
> }
> of_node_put(from);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> }
> EXPORT_SYMBOL(of_find_compatible_node);
> @@ -581,8 +590,9 @@ struct device_node *of_find_node_with_property(struct device_node *from,
> {
> struct device_node *np;
> struct property *pp;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> np = from ? from->allnext : of_allnodes;
> for (; np; np = np->allnext) {
> for (pp = np->properties; pp; pp = pp->next) {
> @@ -594,7 +604,7 @@ struct device_node *of_find_node_with_property(struct device_node *from,
> }
> out:
> of_node_put(from);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> }
> EXPORT_SYMBOL(of_find_node_with_property);
> @@ -635,10 +645,11 @@ const struct of_device_id *of_match_node(const struct of_device_id *matches,
> const struct device_node *node)
> {
> const struct of_device_id *match;
> + unsigned long flags;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> match = __of_match_node(matches, node);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return match;
> }
> EXPORT_SYMBOL(of_match_node);
> @@ -662,11 +673,12 @@ struct device_node *of_find_matching_node_and_match(struct device_node *from,
> {
> struct device_node *np;
> const struct of_device_id *m;
> + unsigned long flags;
>
> if (match)
> *match = NULL;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> np = from ? from->allnext : of_allnodes;
> for (; np; np = np->allnext) {
> m = __of_match_node(matches, np);
> @@ -677,7 +689,7 @@ struct device_node *of_find_matching_node_and_match(struct device_node *from,
> }
> }
> of_node_put(from);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return np;
> }
> EXPORT_SYMBOL(of_find_matching_node_and_match);
> @@ -720,12 +732,12 @@ struct device_node *of_find_node_by_phandle(phandle handle)
> {
> struct device_node *np;
>
> - read_lock(&devtree_lock);
> + raw_spin_lock(&devtree_lock);
> for (np = of_allnodes; np; np = np->allnext)
> if (np->phandle == handle)
> break;
> of_node_get(np);
> - read_unlock(&devtree_lock);
> + raw_spin_unlock(&devtree_lock);
> return np;
> }
> EXPORT_SYMBOL(of_find_node_by_phandle);
> @@ -1197,18 +1209,18 @@ int of_add_property(struct device_node *np, struct property *prop)
> return rc;
>
> prop->next = NULL;
> - write_lock_irqsave(&devtree_lock, flags);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> next = &np->properties;
> while (*next) {
> if (strcmp(prop->name, (*next)->name) == 0) {
> /* duplicate ! don't insert it */
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return -1;
> }
> next = &(*next)->next;
> }
> *next = prop;
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
> #ifdef CONFIG_PROC_DEVICETREE
> /* try to add to proc as well if it was initialized */
> @@ -1238,7 +1250,7 @@ int of_remove_property(struct device_node *np, struct property *prop)
> if (rc)
> return rc;
>
> - write_lock_irqsave(&devtree_lock, flags);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> next = &np->properties;
> while (*next) {
> if (*next == prop) {
> @@ -1251,7 +1263,7 @@ int of_remove_property(struct device_node *np, struct property *prop)
> }
> next = &(*next)->next;
> }
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
> if (!found)
> return -ENODEV;
> @@ -1291,7 +1303,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
> if (!oldprop)
> return of_add_property(np, newprop);
>
> - write_lock_irqsave(&devtree_lock, flags);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> next = &np->properties;
> while (*next) {
> if (*next == oldprop) {
> @@ -1305,7 +1317,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
> }
> next = &(*next)->next;
> }
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
> if (!found)
> return -ENODEV;
> @@ -1378,12 +1390,12 @@ int of_attach_node(struct device_node *np)
> if (rc)
> return rc;
>
> - write_lock_irqsave(&devtree_lock, flags);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
> np->sibling = np->parent->child;
> np->allnext = of_allnodes;
> np->parent->child = np;
> of_allnodes = np;
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
> of_add_proc_dt_entry(np);
> return 0;
> @@ -1426,17 +1438,17 @@ int of_detach_node(struct device_node *np)
> if (rc)
> return rc;
>
> - write_lock_irqsave(&devtree_lock, flags);
> + raw_spin_lock_irqsave(&devtree_lock, flags);
>
> if (of_node_check_flag(np, OF_DETACHED)) {
> /* someone already detached it */
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return rc;
> }
>
> parent = np->parent;
> if (!parent) {
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
> return rc;
> }
>
> @@ -1463,7 +1475,7 @@ int of_detach_node(struct device_node *np)
> }
>
> of_node_set_flag(np, OF_DETACHED);
> - write_unlock_irqrestore(&devtree_lock, flags);
> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
> of_remove_proc_dt_entry(np);
> return rc;
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 5ebcc5c..bb35c42 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -92,7 +92,7 @@ static inline void of_node_put(struct device_node *node) { }
> extern struct device_node *of_allnodes;
> extern struct device_node *of_chosen;
> extern struct device_node *of_aliases;
> -extern rwlock_t devtree_lock;
> +extern raw_spinlock_t devtree_lock;
>
> static inline bool of_have_populated_dt(void)
> {
>
--
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