coredump: elf_core_dump: use core_state->dumper list

Kill the nasty rcu_read_lock() + do_each_thread() loop, use the list
encoded in mm->core_state instead, s/GFP_ATOMIC/GFP_KERNEL/.

This patch allows futher cleanups in binfmt_elf.c, in particular we can
kill the parallel info->threads list.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index bad7d8770d720f1f9090141ccb05104b3ea468ad..88d180306cf942a9f65672ab57b5aad8f46722e0 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1478,7 +1478,7 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
        const struct user_regset_view *view = task_user_regset_view(dump_task);
        struct elf_thread_core_info *t;
        struct elf_prpsinfo *psinfo;
-       struct task_struct *g, *p;
+       struct core_thread *ct;
        unsigned int i;
 
        info->size = 0;
@@ -1517,34 +1517,26 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
        /*
         * Allocate a structure for each thread.
         */
-       rcu_read_lock();
-       do_each_thread(g, p)
-               if (p->mm == dump_task->mm) {
-                       if (p->flags & PF_KTHREAD)
-                               continue;
-
-                       t = kzalloc(offsetof(struct elf_thread_core_info,
-                                            notes[info->thread_notes]),
-                                   GFP_ATOMIC);
-                       if (unlikely(!t)) {
-                               rcu_read_unlock();
-                               return 0;
-                       }
-                       t->task = p;
-                       if (p == dump_task || !info->thread) {
-                               t->next = info->thread;
-                               info->thread = t;
-                       } else {
-                               /*
-                                * Make sure to keep the original task at
-                                * the head of the list.
-                                */
-                               t->next = info->thread->next;
-                               info->thread->next = t;
-                       }
+       for (ct = &dump_task->mm->core_state->dumper; ct; ct = ct->next) {
+               t = kzalloc(offsetof(struct elf_thread_core_info,
+                                    notes[info->thread_notes]),
+                           GFP_KERNEL);
+               if (unlikely(!t))
+                       return 0;
+
+               t->task = ct->task;
+               if (ct->task == dump_task || !info->thread) {
+                       t->next = info->thread;
+                       info->thread = t;
+               } else {
+                       /*
+                        * Make sure to keep the original task at
+                        * the head of the list.
+                        */
+                       t->next = info->thread->next;
+                       info->thread->next = t;
                }
-       while_each_thread(g, p);
-       rcu_read_unlock();
+       }
 
        /*
         * Now fill in each thread's information.
@@ -1691,7 +1683,6 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 {
 #define        NUM_NOTES       6
        struct list_head *t;
-       struct task_struct *g, *p;
 
        info->notes = NULL;
        info->prstatus = NULL;
@@ -1723,23 +1714,19 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 
        info->thread_status_size = 0;
        if (signr) {
+               struct core_thread *ct;
                struct elf_thread_status *ets;
-               rcu_read_lock();
-               do_each_thread(g, p)
-                       if (current->mm == p->mm && current != p) {
-                               if (p->flags & PF_KTHREAD)
-                                       continue;
-
-                               ets = kzalloc(sizeof(*ets), GFP_ATOMIC);
-                               if (!ets) {
-                                       rcu_read_unlock();
-                                       return 0;
-                               }
-                               ets->thread = p;
-                               list_add(&ets->list, &info->thread_list);
-                       }
-               while_each_thread(g, p);
-               rcu_read_unlock();
+
+               for (ct = current->mm->core_state->dumper.next;
+                                               ct; ct = ct->next) {
+                       ets = kzalloc(sizeof(*ets), GFP_KERNEL);
+                       if (!ets)
+                               return 0;
+
+                       ets->thread = ct->task;
+                       list_add(&ets->list, &info->thread_list);
+               }
+
                list_for_each(t, &info->thread_list) {
                        int sz;