[v2,3/3] Replace home-grown linked-lists in FreeBSD's native target with STL lists.
Commit Message
FreeBSD's native target uses linked-lists to keep track of pending fork
events and fake vfork done events. Replace the first list with std::list
and the second with std::forward_list.
gdb/ChangeLog:
* fbsd-nat.c (struct fbsd_fork_info): Remove.
(fbsd_pending_children): Use std::list.
(fbsd_remember_child): Likewise.
(fbsd_is_child_pending): Likewise.
(fbsd_pending_vfork_done): Use std::forward_list.
(fbsd_add_vfork_done): Likewise.
(fbsd_is_vfork_done_pending): Likewise.
(fbsd_next_vfork_done): Likewise.
---
gdb/ChangeLog | 11 +++++++++
gdb/fbsd-nat.c | 71 +++++++++++++++++-----------------------------------------
2 files changed, 32 insertions(+), 50 deletions(-)
Comments
On 2017-08-09 19:47, John Baldwin wrote:
> diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
> index 721e72b85c..c89343a24f 100644
> --- a/gdb/fbsd-nat.c
> +++ b/gdb/fbsd-nat.c
> @@ -41,6 +41,8 @@
> #include "elf-bfd.h"
> #include "fbsd-nat.h"
>
> +#include <list>
> +
> /* Return the name of a file that can be opened to get the symbols for
> the child process identified by PID. */
>
> @@ -712,13 +714,7 @@ fbsd_update_thread_list (struct target_ops *ops)
> sake. FreeBSD versions newer than 9.1 contain both fixes.
> */
>
> -struct fbsd_fork_info
> -{
> - struct fbsd_fork_info *next;
> - ptid_t ptid;
> -};
> -
> -static struct fbsd_fork_info *fbsd_pending_children;
> +static std::list<ptid_t> fbsd_pending_children;
Can't this be a forward_list as well?
The series LGTM otherwise.
Simon
On Wednesday, August 09, 2017 08:16:29 PM Simon Marchi wrote:
> On 2017-08-09 19:47, John Baldwin wrote:
> > diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
> > index 721e72b85c..c89343a24f 100644
> > --- a/gdb/fbsd-nat.c
> > +++ b/gdb/fbsd-nat.c
> > @@ -41,6 +41,8 @@
> > #include "elf-bfd.h"
> > #include "fbsd-nat.h"
> >
> > +#include <list>
> > +
> > /* Return the name of a file that can be opened to get the symbols for
> > the child process identified by PID. */
> >
> > @@ -712,13 +714,7 @@ fbsd_update_thread_list (struct target_ops *ops)
> > sake. FreeBSD versions newer than 9.1 contain both fixes.
> > */
> >
> > -struct fbsd_fork_info
> > -{
> > - struct fbsd_fork_info *next;
> > - ptid_t ptid;
> > -};
> > -
> > -static struct fbsd_fork_info *fbsd_pending_children;
> > +static std::list<ptid_t> fbsd_pending_children;
>
> Can't this be a forward_list as well?
Not trivially. fbsd_is_child_pending has to walk the list looking for a
specific PID and remove that specific list entry (not always the first
entry). Right now this is using the following loop:
for (auto it = fbsd_pending_children.begin ();
it != fbsd_pending_children.end (); it++)
if (it->pid () == pid)
{
ptid_t ptid = *it;
fbsd_pending_children.erase (it);
return ptid;
}
return null_ptid;
I'm not sure if it's legal to do something like this for a forward_list:
for (auto it = fbsd_pending_children.before_begin ();
it + 1 != fbsd_pending_children.end (); it++)
if ((it + 1)->pid () == pid)
{
ptid_t ptid = *(it + 1);
fbsd_pending_childern.erase_after (it);
return ptid;
}
return null_ptid;
Even if it is legal, I'm not sure it is more readable. These lists should
generally be quite small, so I think readability is more important than
optimization in this case.
On 2017-08-09 21:15, John Baldwin wrote:
> On Wednesday, August 09, 2017 08:16:29 PM Simon Marchi wrote:
>> On 2017-08-09 19:47, John Baldwin wrote:
>> > diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
>> > index 721e72b85c..c89343a24f 100644
>> > --- a/gdb/fbsd-nat.c
>> > +++ b/gdb/fbsd-nat.c
>> > @@ -41,6 +41,8 @@
>> > #include "elf-bfd.h"
>> > #include "fbsd-nat.h"
>> >
>> > +#include <list>
>> > +
>> > /* Return the name of a file that can be opened to get the symbols for
>> > the child process identified by PID. */
>> >
>> > @@ -712,13 +714,7 @@ fbsd_update_thread_list (struct target_ops *ops)
>> > sake. FreeBSD versions newer than 9.1 contain both fixes.
>> > */
>> >
>> > -struct fbsd_fork_info
>> > -{
>> > - struct fbsd_fork_info *next;
>> > - ptid_t ptid;
>> > -};
>> > -
>> > -static struct fbsd_fork_info *fbsd_pending_children;
>> > +static std::list<ptid_t> fbsd_pending_children;
>>
>> Can't this be a forward_list as well?
>
> Not trivially. fbsd_is_child_pending has to walk the list looking for
> a
> specific PID and remove that specific list entry (not always the first
> entry). Right now this is using the following loop:
>
> for (auto it = fbsd_pending_children.begin ();
> it != fbsd_pending_children.end (); it++)
> if (it->pid () == pid)
> {
> ptid_t ptid = *it;
> fbsd_pending_children.erase (it);
> return ptid;
> }
> return null_ptid;
>
> I'm not sure if it's legal to do something like this for a
> forward_list:
>
> for (auto it = fbsd_pending_children.before_begin ();
> it + 1 != fbsd_pending_children.end (); it++)
> if ((it + 1)->pid () == pid)
> {
> ptid_t ptid = *(it + 1);
> fbsd_pending_childern.erase_after (it);
> return ptid;
> }
> return null_ptid;
>
> Even if it is legal, I'm not sure it is more readable. These lists
> should
> generally be quite small, so I think readability is more important than
> optimization in this case.
Ah, ok. I thought it could be done trivially, but I can't easily
build-test on FreeBSD right now.
I agree with you.
Simon
@@ -1,5 +1,16 @@
2017-08-07 John Baldwin <jhb@FreeBSD.org>
+ * fbsd-nat.c (struct fbsd_fork_info): Remove.
+ (fbsd_pending_children): Use std::list.
+ (fbsd_remember_child): Likewise.
+ (fbsd_is_child_pending): Likewise.
+ (fbsd_pending_vfork_done): Use std::forward_list.
+ (fbsd_add_vfork_done): Likewise.
+ (fbsd_is_vfork_done_pending): Likewise.
+ (fbsd_next_vfork_done): Likewise.
+
+2017-08-07 John Baldwin <jhb@FreeBSD.org>
+
* fbsd-nat.c [HAVE_KINFO_GETVMMAP] (struct free_deleter): New.
(fbsd_find_memory_regions): Use free_deleter with std::unique_ptr.
[!HAVE_KINFO_GETVMMAP] (fbsd_find_memory_regions): Use std::string
@@ -41,6 +41,8 @@
#include "elf-bfd.h"
#include "fbsd-nat.h"
+#include <list>
+
/* Return the name of a file that can be opened to get the symbols for
the child process identified by PID. */
@@ -712,13 +714,7 @@ fbsd_update_thread_list (struct target_ops *ops)
sake. FreeBSD versions newer than 9.1 contain both fixes.
*/
-struct fbsd_fork_info
-{
- struct fbsd_fork_info *next;
- ptid_t ptid;
-};
-
-static struct fbsd_fork_info *fbsd_pending_children;
+static std::list<ptid_t> fbsd_pending_children;
/* Record a new child process event that is reported before the
corresponding fork event in the parent. */
@@ -726,11 +722,7 @@ static struct fbsd_fork_info *fbsd_pending_children;
static void
fbsd_remember_child (ptid_t pid)
{
- struct fbsd_fork_info *info = XCNEW (struct fbsd_fork_info);
-
- info->ptid = pid;
- info->next = fbsd_pending_children;
- fbsd_pending_children = info;
+ fbsd_pending_children.push_front (pid);
}
/* Check for a previously-recorded new child process event for PID.
@@ -739,39 +731,26 @@ fbsd_remember_child (ptid_t pid)
static ptid_t
fbsd_is_child_pending (pid_t pid)
{
- struct fbsd_fork_info *info, *prev;
- ptid_t ptid;
-
- prev = NULL;
- for (info = fbsd_pending_children; info; prev = info, info = info->next)
- {
- if (ptid_get_pid (info->ptid) == pid)
- {
- if (prev == NULL)
- fbsd_pending_children = info->next;
- else
- prev->next = info->next;
- ptid = info->ptid;
- xfree (info);
- return ptid;
- }
- }
+ for (auto it = fbsd_pending_children.begin ();
+ it != fbsd_pending_children.end (); it++)
+ if (it->pid () == pid)
+ {
+ ptid_t ptid = *it;
+ fbsd_pending_children.erase (it);
+ return ptid;
+ }
return null_ptid;
}
#ifndef PTRACE_VFORK
-static struct fbsd_fork_info *fbsd_pending_vfork_done;
+static std::forward_list<ptid_t> fbsd_pending_vfork_done;
/* Record a pending vfork done event. */
static void
fbsd_add_vfork_done (ptid_t pid)
{
- struct fbsd_fork_info *info = XCNEW (struct fbsd_fork_info);
-
- info->ptid = pid;
- info->next = fbsd_pending_vfork_done;
- fbsd_pending_vfork_done = info;
+ fbsd_pending_vfork_done.push_front (pid);
}
/* Check for a pending vfork done event for a specific PID. */
@@ -779,13 +758,10 @@ fbsd_add_vfork_done (ptid_t pid)
static int
fbsd_is_vfork_done_pending (pid_t pid)
{
- struct fbsd_fork_info *info;
-
- for (info = fbsd_pending_vfork_done; info != NULL; info = info->next)
- {
- if (ptid_get_pid (info->ptid) == pid)
- return 1;
- }
+ for (auto it = fbsd_pending_vfork_done.begin ();
+ it != fbsd_pending_vfork_done.end (); it++)
+ if (it->pid () == pid)
+ return 1;
return 0;
}
@@ -795,15 +771,10 @@ fbsd_is_vfork_done_pending (pid_t pid)
static ptid_t
fbsd_next_vfork_done (void)
{
- struct fbsd_fork_info *info;
- ptid_t ptid;
-
- if (fbsd_pending_vfork_done != NULL)
+ if (!fbsd_pending_vfork_done.empty ())
{
- info = fbsd_pending_vfork_done;
- fbsd_pending_vfork_done = info->next;
- ptid = info->ptid;
- xfree (info);
+ ptid_t ptid = fbsd_pending_vfork_done.front ();
+ fbsd_pending_vfork_done.pop_front ();
return ptid;
}
return null_ptid;