kpriv/linux-hardened
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

don't bother with deferred freeing of fdtables

Browse source 
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2013-04-28 21:42:33 -04:00
parent 094dd33b17
commit ac3e3c5b11
2 changed files with 2 additions and 67 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

68
fs/file.c
View file

@ -23,24 +23,10 @@
#include <linux/rcupdate.h>
#include <linux/workqueue.h>
struct fdtable_defer {
spinlock_t lock;
struct work_struct wq;
struct fdtable *next;
};
int sysctl_nr_open __read_mostly = 1024*1024;
int sysctl_nr_open_min = BITS_PER_LONG;
int sysctl_nr_open_max = 1024 * 1024; /* raised later */
/*
* We use this list to defer free fdtables that have vmalloced
* sets/arrays. By keeping a per-cpu list, we avoid having to embed
* the work_struct in fdtable itself which avoids a 64 byte (i386) increase in
* this per-task structure.
*/
static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
static void *alloc_fdmem(size_t size)
{
/*
@ -67,46 +53,9 @@ static void __free_fdtable(struct fdtable *fdt)
kfree(fdt);
}
static void free_fdtable_work(struct work_struct *work)
{
struct fdtable_defer *f =
container_of(work, struct fdtable_defer, wq);
struct fdtable *fdt;
spin_lock_bh(&f->lock);
fdt = f->next;
f->next = NULL;
spin_unlock_bh(&f->lock);
while(fdt) {
struct fdtable *next = fdt->next;
__free_fdtable(fdt);
fdt = next;
}
}
static void free_fdtable_rcu(struct rcu_head *rcu)
{
struct fdtable *fdt = container_of(rcu, struct fdtable, rcu);
struct fdtable_defer *fddef;
BUG_ON(!fdt);
BUG_ON(fdt->max_fds <= NR_OPEN_DEFAULT);
if (!is_vmalloc_addr(fdt->fd) && !is_vmalloc_addr(fdt->open_fds)) {
kfree(fdt->fd);
kfree(fdt->open_fds);
kfree(fdt);
} else {
fddef = &get_cpu_var(fdtable_defer_list);
spin_lock(&fddef->lock);
fdt->next = fddef->next;
fddef->next = fdt;
/* vmallocs are handled from the workqueue context */
schedule_work(&fddef->wq);
spin_unlock(&fddef->lock);
put_cpu_var(fdtable_defer_list);
}
__free_fdtable(container_of(rcu, struct fdtable, rcu));
}
/*
@ -174,7 +123,6 @@ static struct fdtable * alloc_fdtable(unsigned int nr)
fdt->open_fds = data;
data += nr / BITS_PER_BYTE;
fdt->close_on_exec = data;
fdt->next = NULL;
return fdt;
@ -221,7 +169,7 @@ static int expand_fdtable(struct files_struct *files, int nr)
/* Continue as planned */
copy_fdtable(new_fdt, cur_fdt);
rcu_assign_pointer(files->fdt, new_fdt);
if (cur_fdt->max_fds > NR_OPEN_DEFAULT)
if (cur_fdt != &files->fdtab)
call_rcu(&cur_fdt->rcu, free_fdtable_rcu);
} else {
/* Somebody else expanded, so undo our attempt */
@ -316,7 +264,6 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
new_fdt->close_on_exec = newf->close_on_exec_init;
new_fdt->open_fds = newf->open_fds_init;
new_fdt->fd = &newf->fd_array[0];
new_fdt->next = NULL;
spin_lock(&oldf->file_lock);
old_fdt = files_fdtable(oldf);
@ -490,19 +437,8 @@ void exit_files(struct task_struct *tsk)
}
}
static void fdtable_defer_list_init(int cpu)
{
struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
spin_lock_init(&fddef->lock);
INIT_WORK(&fddef->wq, free_fdtable_work);
fddef->next = NULL;
}
void __init files_defer_init(void)
{
int i;
for_each_possible_cpu(i)
fdtable_defer_list_init(i);
sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) &
-BITS_PER_LONG;
}

1
include/linux/fdtable.h
View file

@ -27,7 +27,6 @@ struct fdtable {
unsigned long *close_on_exec;
unsigned long *open_fds;
struct rcu_head rcu;
struct fdtable *next;
};
static inline bool close_on_exec(int fd, const struct fdtable *fdt)