[PATCH] uml: avoid already done dirtying
[pandora-kernel.git] / kernel / fork.c
index 2c78068..8149f36 100644 (file)
@@ -35,6 +35,7 @@
 #include <linux/syscalls.h>
 #include <linux/jiffies.h>
 #include <linux/futex.h>
+#include <linux/rcupdate.h>
 #include <linux/ptrace.h>
 #include <linux/mount.h>
 #include <linux/audit.h>
@@ -176,6 +177,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 
        /* One for us, one for whoever does the "release_task()" (usually parent) */
        atomic_set(&tsk->usage,2);
+       atomic_set(&tsk->fs_excl, 0);
        return tsk;
 }
 
@@ -208,8 +210,10 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
                struct file *file;
 
                if (mpnt->vm_flags & VM_DONTCOPY) {
+                       long pages = vma_pages(mpnt);
+                       mm->total_vm -= pages;
                        __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
-                                                       -vma_pages(mpnt));
+                                                               -pages);
                        continue;
                }
                charge = 0;
@@ -562,24 +566,53 @@ static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
        return 0;
 }
 
-static int count_open_files(struct files_struct *files, int size)
+static int count_open_files(struct fdtable *fdt)
 {
+       int size = fdt->max_fdset;
        int i;
 
        /* Find the last open fd */
        for (i = size/(8*sizeof(long)); i > 0; ) {
-               if (files->open_fds->fds_bits[--i])
+               if (fdt->open_fds->fds_bits[--i])
                        break;
        }
        i = (i+1) * 8 * sizeof(long);
        return i;
 }
 
+static struct files_struct *alloc_files(void)
+{
+       struct files_struct *newf;
+       struct fdtable *fdt;
+
+       newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
+       if (!newf)
+               goto out;
+
+       atomic_set(&newf->count, 1);
+
+       spin_lock_init(&newf->file_lock);
+       fdt = &newf->fdtab;
+       fdt->next_fd = 0;
+       fdt->max_fds = NR_OPEN_DEFAULT;
+       fdt->max_fdset = __FD_SETSIZE;
+       fdt->close_on_exec = &newf->close_on_exec_init;
+       fdt->open_fds = &newf->open_fds_init;
+       fdt->fd = &newf->fd_array[0];
+       INIT_RCU_HEAD(&fdt->rcu);
+       fdt->free_files = NULL;
+       fdt->next = NULL;
+       rcu_assign_pointer(newf->fdt, fdt);
+out:
+       return newf;
+}
+
 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
 {
        struct files_struct *oldf, *newf;
        struct file **old_fds, **new_fds;
        int open_files, size, i, error = 0, expand;
+       struct fdtable *old_fdt, *new_fdt;
 
        /*
         * A background process may not have any files ...
@@ -600,35 +633,27 @@ static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
         */
        tsk->files = NULL;
        error = -ENOMEM;
-       newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
-       if (!newf) 
+       newf = alloc_files();
+       if (!newf)
                goto out;
 
-       atomic_set(&newf->count, 1);
-
-       spin_lock_init(&newf->file_lock);
-       newf->next_fd       = 0;
-       newf->max_fds       = NR_OPEN_DEFAULT;
-       newf->max_fdset     = __FD_SETSIZE;
-       newf->close_on_exec = &newf->close_on_exec_init;
-       newf->open_fds      = &newf->open_fds_init;
-       newf->fd            = &newf->fd_array[0];
-
        spin_lock(&oldf->file_lock);
-
-       open_files = count_open_files(oldf, oldf->max_fdset);
+       old_fdt = files_fdtable(oldf);
+       new_fdt = files_fdtable(newf);
+       size = old_fdt->max_fdset;
+       open_files = count_open_files(old_fdt);
        expand = 0;
 
        /*
         * Check whether we need to allocate a larger fd array or fd set.
         * Note: we're not a clone task, so the open count won't  change.
         */
-       if (open_files > newf->max_fdset) {
-               newf->max_fdset = 0;
+       if (open_files > new_fdt->max_fdset) {
+               new_fdt->max_fdset = 0;
                expand = 1;
        }
-       if (open_files > newf->max_fds) {
-               newf->max_fds = 0;
+       if (open_files > new_fdt->max_fds) {
+               new_fdt->max_fds = 0;
                expand = 1;
        }
 
@@ -640,14 +665,21 @@ static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
                spin_unlock(&newf->file_lock);
                if (error < 0)
                        goto out_release;
+               new_fdt = files_fdtable(newf);
+               /*
+                * Reacquire the oldf lock and a pointer to its fd table
+                * who knows it may have a new bigger fd table. We need
+                * the latest pointer.
+                */
                spin_lock(&oldf->file_lock);
+               old_fdt = files_fdtable(oldf);
        }
 
-       old_fds = oldf->fd;
-       new_fds = newf->fd;
+       old_fds = old_fdt->fd;
+       new_fds = new_fdt->fd;
 
-       memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8);
-       memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8);
+       memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
+       memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
 
        for (i = open_files; i != 0; i--) {
                struct file *f = *old_fds++;
@@ -660,24 +692,24 @@ static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
                         * is partway through open().  So make sure that this
                         * fd is available to the new process.
                         */
-                       FD_CLR(open_files - i, newf->open_fds);
+                       FD_CLR(open_files - i, new_fdt->open_fds);
                }
-               *new_fds++ = f;
+               rcu_assign_pointer(*new_fds++, f);
        }
        spin_unlock(&oldf->file_lock);
 
        /* compute the remainder to be cleared */
-       size = (newf->max_fds - open_files) * sizeof(struct file *);
+       size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
 
        /* This is long word aligned thus could use a optimized version */ 
        memset(new_fds, 0, size); 
 
-       if (newf->max_fdset > open_files) {
-               int left = (newf->max_fdset-open_files)/8;
+       if (new_fdt->max_fdset > open_files) {
+               int left = (new_fdt->max_fdset-open_files)/8;
                int start = open_files / (8 * sizeof(unsigned long));
 
-               memset(&newf->open_fds->fds_bits[start], 0, left);
-               memset(&newf->close_on_exec->fds_bits[start], 0, left);
+               memset(&new_fdt->open_fds->fds_bits[start], 0, left);
+               memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
        }
 
        tsk->files = newf;
@@ -686,9 +718,9 @@ out:
        return error;
 
 out_release:
-       free_fdset (newf->close_on_exec, newf->max_fdset);
-       free_fdset (newf->open_fds, newf->max_fdset);
-       free_fd_array(newf->fd, newf->max_fds);
+       free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
+       free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
+       free_fd_array(new_fdt->fd, new_fdt->max_fds);
        kmem_cache_free(files_cachep, newf);
        goto out;
 }
@@ -992,6 +1024,9 @@ static task_t *copy_process(unsigned long clone_flags,
         * of CLONE_PTRACE.
         */
        clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
+#ifdef TIF_SYSCALL_EMU
+       clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
+#endif
 
        /* Our parent execution domain becomes current domain
           These must match for thread signalling to apply */
@@ -1090,6 +1125,11 @@ static task_t *copy_process(unsigned long clone_flags,
                spin_unlock(&current->sighand->siglock);
        }
 
+       /*
+        * inherit ioprio
+        */
+       p->ioprio = current->ioprio;
+
        SET_LINKS(p);
        if (unlikely(p->ptrace & PT_PTRACED))
                __ptrace_link(p, current->parent);
@@ -1105,6 +1145,9 @@ static task_t *copy_process(unsigned long clone_flags,
                        __get_cpu_var(process_counts)++;
        }
 
+       if (!current->signal->tty && p->signal->tty)
+               p->signal->tty = NULL;
+
        nr_threads++;
        total_forks++;
        write_unlock_irq(&tasklist_lock);