while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org --- drivers/clk/clk.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..f896584 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1048,10 +1048,7 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
hlist_del(&clk->child_node);
- if (new_parent) - hlist_add_head(&clk->child_node, &new_parent->children); - else - hlist_add_head(&clk->child_node, &clk_orphan_list); + hlist_add_head(&clk->child_node, &new_parent->children);
#ifdef CONFIG_COMMON_CLK_DEBUG if (!inited)
On 01/08/2013 06:33 PM, Rajagopal Venkat wrote:
while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org
drivers/clk/clk.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..f896584 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1048,10 +1048,7 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) hlist_del(&clk->child_node);
- if (new_parent)
hlist_add_head(&clk->child_node, &new_parent->children);- else
hlist_add_head(&clk->child_node, &clk_orphan_list);
- hlist_add_head(&clk->child_node, &new_parent->children);
#ifdef CONFIG_COMMON_CLK_DEBUG if (!inited)
The same logic holds good for following piece of code too.
1060 |-------if (new_parent) 1061 |-------|-------new_parent_d = new_parent->dentry; 1062 |-------else 1063 |-------|-------new_parent_d = orphandir;
On 9 January 2013 11:20, Tushar Behera tushar.behera@linaro.org wrote:
On 01/08/2013 06:33 PM, Rajagopal Venkat wrote:
while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org
drivers/clk/clk.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..f896584 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1048,10 +1048,7 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
hlist_del(&clk->child_node);
if (new_parent)hlist_add_head(&clk->child_node, &new_parent->children);elsehlist_add_head(&clk->child_node, &clk_orphan_list);
hlist_add_head(&clk->child_node, &new_parent->children);#ifdef CONFIG_COMMON_CLK_DEBUG if (!inited)
The same logic holds good for following piece of code too.
1060 |-------if (new_parent) 1061 |-------|-------new_parent_d = new_parent->dentry; 1062 |-------else 1063 |-------|-------new_parent_d = orphandir;
Yes. Thanks for pointing out.
-- Tushar Behera
while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org --- drivers/clk/clk.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..1c4097c 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1040,7 +1040,6 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) { #ifdef CONFIG_COMMON_CLK_DEBUG struct dentry *d; - struct dentry *new_parent_d; #endif
if (!clk || !new_parent) @@ -1048,22 +1047,14 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
hlist_del(&clk->child_node);
- if (new_parent) - hlist_add_head(&clk->child_node, &new_parent->children); - else - hlist_add_head(&clk->child_node, &clk_orphan_list); + hlist_add_head(&clk->child_node, &new_parent->children);
#ifdef CONFIG_COMMON_CLK_DEBUG if (!inited) goto out;
- if (new_parent) - new_parent_d = new_parent->dentry; - else - new_parent_d = orphandir; - d = debugfs_rename(clk->dentry->d_parent, clk->dentry, - new_parent_d, clk->name); + new_parent->dentry, clk->name); if (d) clk->dentry = d; else
On 01/09/2013 11:59 AM, Rajagopal Venkat wrote:
while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org
It is good to have revision history of the patches (version number and changelog).
drivers/clk/clk.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..1c4097c 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1040,7 +1040,6 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) { #ifdef CONFIG_COMMON_CLK_DEBUG struct dentry *d;
- struct dentry *new_parent_d;
#endif if (!clk || !new_parent) @@ -1048,22 +1047,14 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) hlist_del(&clk->child_node);
- if (new_parent)
hlist_add_head(&clk->child_node, &new_parent->children);- else
hlist_add_head(&clk->child_node, &clk_orphan_list);
- hlist_add_head(&clk->child_node, &new_parent->children);
#ifdef CONFIG_COMMON_CLK_DEBUG if (!inited) goto out;
- if (new_parent)
new_parent_d = new_parent->dentry;- else
new_parent_d = orphandir;- d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
new_parent_d, clk->name);
new_parent->dentry, clk->name);
Quoting Rajagopal Venkat (2013-01-08 22:29:48)
while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org
drivers/clk/clk.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..1c4097c 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1040,7 +1040,6 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) { #ifdef CONFIG_COMMON_CLK_DEBUG struct dentry *d;
struct dentry *new_parent_d;#endif if (!clk || !new_parent) @@ -1048,22 +1047,14 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) hlist_del(&clk->child_node);
if (new_parent)hlist_add_head(&clk->child_node, &new_parent->children);elsehlist_add_head(&clk->child_node, &clk_orphan_list);
hlist_add_head(&clk->child_node, &new_parent->children);
Rajagopal,
You found a bug, but not the right one :)
This change would result in never moving a clock into the orphan list if the parent is missing. The right thing to do is to allow the operation to succeed and migrate this clock into the orphan list. In keeping with the clk.h api we need to treat struct clk new_parent as an opaque cookie and not care whether or not it is NULL.
Untested patch below fixes the real bug:
From a4d56e3ee51452366365749873710e16631e9de7 Mon Sep 17 00:00:00 2001 From: Mike Turquette mturquette@linaro.org Date: Tue, 15 Jan 2013 14:39:06 -0800 Subject: [PATCH] clk: allow re-parenting to NULL clks
__clk_reparent presently bails early if the new parent of a clk is NULL. This is wrong and prevents dynamically migrating clocks into the orphan list. The fix is to remove the NULL pointer check for new_parent in __clk_parent.
Signed-off-by: Mike Turquette mturquette@linaro.org --- drivers/clk/clk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 593a2e4..f056230 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1186,7 +1186,7 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) struct dentry *new_parent_d; #endif
- if (!clk || !new_parent) + if (!clk) return;
hlist_del(&clk->child_node);
On 16 January 2013 04:15, Mike Turquette mturquette@linaro.org wrote:
Quoting Rajagopal Venkat (2013-01-08 22:29:48)
while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org
drivers/clk/clk.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..1c4097c 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1040,7 +1040,6 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) { #ifdef CONFIG_COMMON_CLK_DEBUG struct dentry *d;
struct dentry *new_parent_d;#endif
if (!clk || !new_parent)@@ -1048,22 +1047,14 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
hlist_del(&clk->child_node);
if (new_parent)hlist_add_head(&clk->child_node, &new_parent->children);elsehlist_add_head(&clk->child_node, &clk_orphan_list);
hlist_add_head(&clk->child_node, &new_parent->children);Rajagopal,
You found a bug, but not the right one :)
This change would result in never moving a clock into the orphan list if the parent is missing. The right thing to do is to allow the operation to succeed and migrate this clock into the orphan list. In keeping with the clk.h api we need to treat struct clk new_parent as an opaque cookie and not care whether or not it is NULL.
Mike,
The only path where __clk_reparent() can get new parent as NULL is from clk_set_parent() api. Tracing this path, here are the reasons why I submitted this patch.
1. The clk_set_parent() function takes new parent for granted and tries to access new_parent->rate when notifiers are registered, 2. For clocks with multiple parents, the __clk_set_parent() function also takes new parent for granted and tries to access parent name while finding the index of new parent from cached parent pointers.
But if the design decision is to allow clock to be re-parented to orphan list when new parent is missing, I can provide the new working patch.
Untested patch below fixes the real bug:
From a4d56e3ee51452366365749873710e16631e9de7 Mon Sep 17 00:00:00 2001 From: Mike Turquette mturquette@linaro.org Date: Tue, 15 Jan 2013 14:39:06 -0800 Subject: [PATCH] clk: allow re-parenting to NULL clks
__clk_reparent presently bails early if the new parent of a clk is NULL. This is wrong and prevents dynamically migrating clocks into the orphan list. The fix is to remove the NULL pointer check for new_parent in __clk_parent.
Signed-off-by: Mike Turquette mturquette@linaro.org
drivers/clk/clk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 593a2e4..f056230 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1186,7 +1186,7 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) struct dentry *new_parent_d; #endif
if (!clk || !new_parent)
if (!clk) return; hlist_del(&clk->child_node);-- 1.7.10.4
Quoting Rajagopal Venkat (2013-01-16 04:45:13)
On 16 January 2013 04:15, Mike Turquette mturquette@linaro.org wrote:
Quoting Rajagopal Venkat (2013-01-08 22:29:48)
while reparenting a clock, NULL check is done for clock in consideration and its new parent. So re-check is not required. If done, else part becomes unreachable.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org
drivers/clk/clk.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 251e45d..1c4097c 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1040,7 +1040,6 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) { #ifdef CONFIG_COMMON_CLK_DEBUG struct dentry *d;
struct dentry *new_parent_d;#endif
if (!clk || !new_parent)@@ -1048,22 +1047,14 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
hlist_del(&clk->child_node);
if (new_parent)hlist_add_head(&clk->child_node, &new_parent->children);elsehlist_add_head(&clk->child_node, &clk_orphan_list);
hlist_add_head(&clk->child_node, &new_parent->children);Rajagopal,
You found a bug, but not the right one :)
This change would result in never moving a clock into the orphan list if the parent is missing. The right thing to do is to allow the operation to succeed and migrate this clock into the orphan list. In keeping with the clk.h api we need to treat struct clk new_parent as an opaque cookie and not care whether or not it is NULL.
Mike,
The only path where __clk_reparent() can get new parent as NULL is from clk_set_parent() api. Tracing this path, here are the reasons why I submitted this patch.
- The clk_set_parent() function takes new parent for granted and tries to
access new_parent->rate when notifiers are registered, 2. For clocks with multiple parents, the __clk_set_parent() function also takes new parent for granted and tries to access parent name while finding the index of new parent from cached parent pointers.
But if the design decision is to allow clock to be re-parented to orphan list when new parent is missing, I can provide the new working patch.
Rajagopal,
Yes, reparenting a clock to the orphan list should be supported. Let me know if you are going to spin a new patch or not.
Thanks, Mike
Untested patch below fixes the real bug:
From a4d56e3ee51452366365749873710e16631e9de7 Mon Sep 17 00:00:00 2001 From: Mike Turquette mturquette@linaro.org Date: Tue, 15 Jan 2013 14:39:06 -0800 Subject: [PATCH] clk: allow re-parenting to NULL clks
__clk_reparent presently bails early if the new parent of a clk is NULL. This is wrong and prevents dynamically migrating clocks into the orphan list. The fix is to remove the NULL pointer check for new_parent in __clk_parent.
Signed-off-by: Mike Turquette mturquette@linaro.org
drivers/clk/clk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 593a2e4..f056230 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1186,7 +1186,7 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) struct dentry *new_parent_d; #endif
if (!clk || !new_parent)
if (!clk) return; hlist_del(&clk->child_node);-- 1.7.10.4
-- Regards, Rajagopal
-
Mike Turquette -
Rajagopal Venkat -
Tushar Behera