remove libdss from Makefile

[GitHub/moto-9609/android_kernel_motorola_exynos9610.git] / fs / aio.c

diff --git a/fs/aio.c b/fs/aio.c
index 5a2487217072d18b1b5a25b6961e6cdd938375fc..a2de58f77338d05bd0f27dd0d565dcea61f779b5 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -43,6 +43,7 @@
 
 #include <asm/kmap_types.h>
 #include <linux/uaccess.h>
+#include <linux/nospec.h>
 
 #include "internal.h"
 
@@ -68,9 +69,9 @@ struct aio_ring {
 #define AIO_RING_PAGES 8
 
 struct kioctx_table {
-       struct rcu_head rcu;
-       unsigned        nr;
-       struct kioctx   *table[];
+       struct rcu_head         rcu;
+       unsigned                nr;
+       struct kioctx __rcu     *table[];
 };
 
 struct kioctx_cpu {
@@ -115,7 +116,8 @@ struct kioctx {
        struct page             **ring_pages;
        long                    nr_pages;
 
-       struct work_struct      free_work;
+       struct rcu_head         free_rcu;
+       struct work_struct      free_work;      /* see free_ioctx() */
 
        /*
         * signals when all in-flight requests are done
@@ -329,7 +331,7 @@ static int aio_ring_mremap(struct vm_area_struct *vma)
        for (i = 0; i < table->nr; i++) {
                struct kioctx *ctx;
 
-               ctx = table->table[i];
+               ctx = rcu_dereference(table->table[i]);
                if (ctx && ctx->aio_ring_file == file) {
                        if (!atomic_read(&ctx->dead)) {
                                ctx->user_id = ctx->mmap_base = vma->vm_start;
@@ -588,6 +590,12 @@ static int kiocb_cancel(struct aio_kiocb *kiocb)
        return cancel(&kiocb->common);
 }
 
+/*
+ * free_ioctx() should be RCU delayed to synchronize against the RCU
+ * protected lookup_ioctx() and also needs process context to call
+ * aio_free_ring(), so the double bouncing through kioctx->free_rcu and
+ * ->free_work.
+ */
 static void free_ioctx(struct work_struct *work)
 {
        struct kioctx *ctx = container_of(work, struct kioctx, free_work);
@@ -601,6 +609,14 @@ static void free_ioctx(struct work_struct *work)
        kmem_cache_free(kioctx_cachep, ctx);
 }
 
+static void free_ioctx_rcufn(struct rcu_head *head)
+{
+       struct kioctx *ctx = container_of(head, struct kioctx, free_rcu);
+
+       INIT_WORK(&ctx->free_work, free_ioctx);
+       schedule_work(&ctx->free_work);
+}
+
 static void free_ioctx_reqs(struct percpu_ref *ref)
 {
        struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
@@ -609,8 +625,8 @@ static void free_ioctx_reqs(struct percpu_ref *ref)
        if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
                complete(&ctx->rq_wait->comp);
 
-       INIT_WORK(&ctx->free_work, free_ioctx);
-       schedule_work(&ctx->free_work);
+       /* Synchronize against RCU protected table->table[] dereferences */
+       call_rcu(&ctx->free_rcu, free_ioctx_rcufn);
 }
 
 /*
@@ -628,9 +644,8 @@ static void free_ioctx_users(struct percpu_ref *ref)
        while (!list_empty(&ctx->active_reqs)) {
                req = list_first_entry(&ctx->active_reqs,
                                       struct aio_kiocb, ki_list);
-
-               list_del_init(&req->ki_list);
                kiocb_cancel(req);
+               list_del_init(&req->ki_list);
        }
 
        spin_unlock_irq(&ctx->ctx_lock);
@@ -651,9 +666,9 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
        while (1) {
                if (table)
                        for (i = 0; i < table->nr; i++)
-                               if (!table->table[i]) {
+                               if (!rcu_access_pointer(table->table[i])) {
                                        ctx->id = i;
-                                       table->table[i] = ctx;
+                                       rcu_assign_pointer(table->table[i], ctx);
                                        spin_unlock(&mm->ioctx_lock);
 
                                        /* While kioctx setup is in progress,
@@ -834,11 +849,11 @@ static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
        }
 
        table = rcu_dereference_raw(mm->ioctx_table);
-       WARN_ON(ctx != table->table[ctx->id]);
-       table->table[ctx->id] = NULL;
+       WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
+       RCU_INIT_POINTER(table->table[ctx->id], NULL);
        spin_unlock(&mm->ioctx_lock);
 
-       /* percpu_ref_kill() will do the necessary call_rcu() */
+       /* free_ioctx_reqs() will do the necessary RCU synchronization */
        wake_up_all(&ctx->wait);
 
        /*
@@ -880,7 +895,8 @@ void exit_aio(struct mm_struct *mm)
 
        skipped = 0;
        for (i = 0; i < table->nr; ++i) {
-               struct kioctx *ctx = table->table[i];
+               struct kioctx *ctx =
+                       rcu_dereference_protected(table->table[i], true);
 
                if (!ctx) {
                        skipped++;
@@ -1069,10 +1085,11 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
        if (!table || id >= table->nr)
                goto out;
 
-       ctx = table->table[id];
+       id = array_index_nospec(id, table->nr);
+       ctx = rcu_dereference(table->table[id]);
        if (ctx && ctx->user_id == ctx_id) {
-               percpu_ref_get(&ctx->users);
-               ret = ctx;
+               if (percpu_ref_tryget_live(&ctx->users))
+                       ret = ctx;
        }
 out:
        rcu_read_unlock();