6 files changed, 190 insertions, 102 deletions

diff --git a/drivers/char/hvc_iucv.c b/drivers/char/hvc_iucv.c
index 21681a81cc35..37b0542a4eeb 100644
--- a/drivers/char/hvc_iucv.c
+++ b/drivers/char/hvc_iucv.c
@@ -139,6 +139,8 @@ struct hvc_iucv_private *hvc_iucv_get_private(uint32_t num)
  *
  * This function allocates a new struct iucv_tty_buffer element and, optionally,
  * allocates an internal data buffer with the specified size @size.
+ * The internal data buffer is always allocated with GFP_DMA which is
+ * required for receiving and sending data with IUCV.
  * Note: The total message size arises from the internal buffer size and the
  *       members of the iucv_tty_msg structure.
  * The function returns NULL if memory allocation has failed.
@@ -154,7 +156,7 @@ static struct iucv_tty_buffer *alloc_tty_buffer(size_t size, gfp_t flags)
 
         if (size > 0) {
                 bufp->msg.length = MSG_SIZE(size);
-                bufp->mbuf = kmalloc(bufp->msg.length, flags);
+                bufp->mbuf = kmalloc(bufp->msg.length, flags | GFP_DMA);
                 if (!bufp->mbuf) {
                         mempool_free(bufp, hvc_iucv_mempool);
                         return NULL;
@@ -237,7 +239,7 @@ static int hvc_iucv_write(struct hvc_iucv_private *priv,
         if (!rb->mbuf) { /* message not yet received ... */
                 /* allocate mem to store msg data; if no memory is available
                  * then leave the buffer on the list and re-try later */
-                rb->mbuf = kmalloc(rb->msg.length, GFP_ATOMIC);
+                rb->mbuf = kmalloc(rb->msg.length, GFP_ATOMIC | GFP_DMA);
                 if (!rb->mbuf)
                         return -ENOMEM;
 
diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 176f1751237f..4462b113ba3f 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -295,6 +295,9 @@ struct smi_info {
 static int force_kipmid[SI_MAX_PARMS];
 static int num_force_kipmid;
 
+static unsigned int kipmid_max_busy_us[SI_MAX_PARMS];
+static int num_max_busy_us;
+
 static int unload_when_empty = 1;
 
 static int try_smi_init(struct smi_info *smi);
@@ -925,23 +928,77 @@ static void set_run_to_completion(void *send_info, int i_run_to_completion)
         }
 }
 
+/*
+ * Use -1 in the nsec value of the busy waiting timespec to tell that
+ * we are spinning in kipmid looking for something and not delaying
+ * between checks
+ */
+static inline void ipmi_si_set_not_busy(struct timespec *ts)
+{
+        ts->tv_nsec = -1;
+}
+static inline int ipmi_si_is_busy(struct timespec *ts)
+{
+        return ts->tv_nsec != -1;
+}
+
+static int ipmi_thread_busy_wait(enum si_sm_result smi_result,
+                                 const struct smi_info *smi_info,
+                                 struct timespec *busy_until)
+{
+        unsigned int max_busy_us = 0;
+
+        if (smi_info->intf_num < num_max_busy_us)
+                max_busy_us = kipmid_max_busy_us[smi_info->intf_num];
+        if (max_busy_us == 0 || smi_result != SI_SM_CALL_WITH_DELAY)
+                ipmi_si_set_not_busy(busy_until);
+        else if (!ipmi_si_is_busy(busy_until)) {
+                getnstimeofday(busy_until);
+                timespec_add_ns(busy_until, max_busy_us*NSEC_PER_USEC);
+        } else {
+                struct timespec now;
+                getnstimeofday(&now);
+                if (unlikely(timespec_compare(&now, busy_until) > 0)) {
+                        ipmi_si_set_not_busy(busy_until);
+                        return 0;
+                }
+        }
+        return 1;
+}
+
+
+/*
+ * A busy-waiting loop for speeding up IPMI operation.
+ *
+ * Lousy hardware makes this hard.  This is only enabled for systems
+ * that are not BT and do not have interrupts.  It starts spinning
+ * when an operation is complete or until max_busy tells it to stop
+ * (if that is enabled).  See the paragraph on kimid_max_busy_us in
+ * Documentation/IPMI.txt for details.
+ */
 static int ipmi_thread(void *data)
 {
         struct smi_info *smi_info = data;
         unsigned long flags;
         enum si_sm_result smi_result;
+        struct timespec busy_until;
 
+        ipmi_si_set_not_busy(&busy_until);
         set_user_nice(current, 19);
         while (!kthread_should_stop()) {
+                int busy_wait;
+
                 spin_lock_irqsave(&(smi_info->si_lock), flags);
                 smi_result = smi_event_handler(smi_info, 0);
                 spin_unlock_irqrestore(&(smi_info->si_lock), flags);
+                busy_wait = ipmi_thread_busy_wait(smi_result, smi_info,
+                                                  &busy_until);
                 if (smi_result == SI_SM_CALL_WITHOUT_DELAY)
                         ; /* do nothing */
-                else if (smi_result == SI_SM_CALL_WITH_DELAY)
+                else if (smi_result == SI_SM_CALL_WITH_DELAY && busy_wait)
                         schedule();
                 else
-                        schedule_timeout_interruptible(1);
+                        schedule_timeout_interruptible(0);
         }
         return 0;
 }
@@ -1144,7 +1201,7 @@ static int           regsizes[SI_MAX_PARMS];
 static unsigned int num_regsizes;
 static int           regshifts[SI_MAX_PARMS];
 static unsigned int num_regshifts;
-static int slave_addrs[SI_MAX_PARMS];
+static int slave_addrs[SI_MAX_PARMS]; /* Leaving 0 chooses the default value */
 static unsigned int num_slave_addrs;
 
 #define IPMI_IO_ADDR_SPACE  0
@@ -1212,6 +1269,11 @@ module_param(unload_when_empty, int, 0);
 MODULE_PARM_DESC(unload_when_empty, "Unload the module if no interfaces are"
                  " specified or found, default is 1.  Setting to 0"
                  " is useful for hot add of devices using hotmod.");
+module_param_array(kipmid_max_busy_us, uint, &num_max_busy_us, 0644);
+MODULE_PARM_DESC(kipmid_max_busy_us,
+                 "Max time (in microseconds) to busy-wait for IPMI data before"
+                 " sleeping. 0 (default) means to wait forever. Set to 100-500"
+                 " if kipmid is using up a lot of CPU time.");
 
 
 static void std_irq_cleanup(struct smi_info *info)
@@ -1607,7 +1669,7 @@ static int hotmod_handler(const char *val, struct kernel_param *kp)
                 regsize = 1;
                 regshift = 0;
                 irq = 0;
-                ipmb = 0x20;
+                ipmb = 0; /* Choose the default if not specified */
 
                 next = strchr(curr, ':');
                 if (next) {
@@ -1799,6 +1861,7 @@ static __devinit void hardcode_find_bmc(void)
                 info->irq = irqs[i];
                 if (info->irq)
                         info->irq_setup = std_irq_setup;
+                info->slave_addr = slave_addrs[i];
 
                 try_smi_init(info);
         }
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 48788db4e280..1f3215ac085b 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -3,7 +3,7 @@
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *
- *  Added devfs support. 
+ *  Added devfs support.
  *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
  *  Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
  */
@@ -44,36 +44,6 @@ static inline unsigned long size_inside_page(unsigned long start,
         return min(sz, size);
 }
 
-/*
- * Architectures vary in how they handle caching for addresses
- * outside of main memory.
- *
- */
-static inline int uncached_access(struct file *file, unsigned long addr)
-{
-#if defined(CONFIG_IA64)
-        /*
-         * On ia64, we ignore O_DSYNC because we cannot tolerate memory attribute aliases.
-         */
-        return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
-#elif defined(CONFIG_MIPS)
-        {
-                extern int __uncached_access(struct file *file,
-                                             unsigned long addr);
-
-                return __uncached_access(file, addr);
-        }
-#else
-        /*
-         * Accessing memory above the top the kernel knows about or through a file pointer
-         * that was marked O_DSYNC will be done non-cached.
-         */
-        if (file->f_flags & O_DSYNC)
-                return 1;
-        return addr >= __pa(high_memory);
-#endif
-}
-
 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
 static inline int valid_phys_addr_range(unsigned long addr, size_t count)
 {
@@ -115,15 +85,15 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 }
 #endif
 
-void __attribute__((weak)) unxlate_dev_mem_ptr(unsigned long phys, void *addr)
+void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
 {
 }
 
 /*
- * This funcion reads the *physical* memory. The f_pos points directly to the 
- * memory location. 
+ * This funcion reads the *physical* memory. The f_pos points directly to the
+ * memory location.
  */
-static ssize_t read_mem(struct file * file, char __user * buf,
+static ssize_t read_mem(struct file *file, char __user *buf,
                         size_t count, loff_t *ppos)
 {
         unsigned long p = *ppos;
@@ -140,10 +110,10 @@ static ssize_t read_mem(struct file * file, char __user * buf,
                 if (sz > 0) {
                         if (clear_user(buf, sz))
                                 return -EFAULT;
-                        buf += sz; 
-                        p += sz; 
-                        count -= sz; 
-                        read += sz; 
+                        buf += sz;
+                        p += sz;
+                        count -= sz;
+                        read += sz;
                 }
         }
 #endif
@@ -157,9 +127,9 @@ static ssize_t read_mem(struct file * file, char __user * buf,
                         return -EPERM;
 
                 /*
-                 * On ia64 if a page has been mapped somewhere as
-                 * uncached, then it must also be accessed uncached
-                 * by the kernel or data corruption may occur
+                 * On ia64 if a page has been mapped somewhere as uncached, then
+                 * it must also be accessed uncached by the kernel or data
+                 * corruption may occur.
                  */
                 ptr = xlate_dev_mem_ptr(p);
                 if (!ptr)
@@ -180,7 +150,7 @@ static ssize_t read_mem(struct file * file, char __user * buf,
         return read;
 }
 
-static ssize_t write_mem(struct file * file, const char __user * buf, 
+static ssize_t write_mem(struct file *file, const char __user *buf,
                          size_t count, loff_t *ppos)
 {
         unsigned long p = *ppos;
@@ -212,9 +182,9 @@ static ssize_t write_mem(struct file * file, const char __user * buf,
                         return -EPERM;
 
                 /*
-                 * On ia64 if a page has been mapped somewhere as
-                 * uncached, then it must also be accessed uncached
-                 * by the kernel or data corruption may occur
+                 * On ia64 if a page has been mapped somewhere as uncached, then
+                 * it must also be accessed uncached by the kernel or data
+                 * corruption may occur.
                  */
                 ptr = xlate_dev_mem_ptr(p);
                 if (!ptr) {
@@ -242,13 +212,46 @@ static ssize_t write_mem(struct file * file, const char __user * buf,
         return written;
 }
 
-int __attribute__((weak)) phys_mem_access_prot_allowed(struct file *file,
+int __weak phys_mem_access_prot_allowed(struct file *file,
         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
 {
         return 1;
 }
 
 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
+
+/*
+ * Architectures vary in how they handle caching for addresses
+ * outside of main memory.
+ *
+ */
+static int uncached_access(struct file *file, unsigned long addr)
+{
+#if defined(CONFIG_IA64)
+        /*
+         * On ia64, we ignore O_DSYNC because we cannot tolerate memory
+         * attribute aliases.
+         */
+        return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
+#elif defined(CONFIG_MIPS)
+        {
+                extern int __uncached_access(struct file *file,
+                                             unsigned long addr);
+
+                return __uncached_access(file, addr);
+        }
+#else
+        /*
+         * Accessing memory above the top the kernel knows about or through a
+         * file pointer
+         * that was marked O_DSYNC will be done non-cached.
+         */
+        if (file->f_flags & O_DSYNC)
+                return 1;
+        return addr >= __pa(high_memory);
+#endif
+}
+
 static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
                                      unsigned long size, pgprot_t vma_prot)
 {
@@ -294,7 +297,7 @@ static const struct vm_operations_struct mmap_mem_ops = {
 #endif
 };
 
-static int mmap_mem(struct file * file, struct vm_area_struct * vma)
+static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 {
         size_t size = vma->vm_end - vma->vm_start;
 
@@ -329,7 +332,7 @@ static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 }
 
 #ifdef CONFIG_DEVKMEM
-static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
+static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 {
         unsigned long pfn;
 
@@ -337,9 +340,9 @@ static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 
         /*
-         * RED-PEN: on some architectures there is more mapped memory
-         * than available in mem_map which pfn_valid checks
-         * for. Perhaps should add a new macro here.
+         * RED-PEN: on some architectures there is more mapped memory than
+         * available in mem_map which pfn_valid checks for. Perhaps should add a
+         * new macro here.
          *
          * RED-PEN: vmalloc is not supported right now.
          */
@@ -389,7 +392,7 @@ static ssize_t read_oldmem(struct file *file, char __user *buf,
 /*
  * This function reads the *virtual* memory as seen by the kernel.
  */
-static ssize_t read_kmem(struct file *file, char __user *buf, 
+static ssize_t read_kmem(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
 {
         unsigned long p = *ppos;
@@ -400,8 +403,8 @@ static ssize_t read_kmem(struct file *file, char __user *buf,
         read = 0;
         if (p < (unsigned long) high_memory) {
                 low_count = count;
-                if (count > (unsigned long) high_memory - p)
-                        low_count = (unsigned long) high_memory - p;
+                if (count > (unsigned long)high_memory - p)
+                        low_count = (unsigned long)high_memory - p;
 
 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
                 /* we don't have page 0 mapped on sparc and m68k.. */
@@ -465,9 +468,8 @@ static ssize_t read_kmem(struct file *file, char __user *buf,
 }
 
 
-static inline ssize_t
-do_write_kmem(unsigned long p, const char __user *buf,
-              size_t count, loff_t *ppos)
+static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
+                                size_t count, loff_t *ppos)
 {
         ssize_t written, sz;
         unsigned long copied;
@@ -491,9 +493,9 @@ do_write_kmem(unsigned long p, const char __user *buf,
                 sz = size_inside_page(p, count);
 
                 /*
-                 * On ia64 if a page has been mapped somewhere as
-                 * uncached, then it must also be accessed uncached
-                 * by the kernel or data corruption may occur
+                 * On ia64 if a page has been mapped somewhere as uncached, then
+                 * it must also be accessed uncached by the kernel or data
+                 * corruption may occur.
                  */
                 ptr = xlate_dev_kmem_ptr((char *)p);
 
@@ -514,11 +516,10 @@ do_write_kmem(unsigned long p, const char __user *buf,
         return written;
 }
 
-
 /*
  * This function writes to the *virtual* memory as seen by the kernel.
  */
-static ssize_t write_kmem(struct file * file, const char __user * buf, 
+static ssize_t write_kmem(struct file *file, const char __user *buf,
                           size_t count, loff_t *ppos)
 {
         unsigned long p = *ppos;
@@ -570,17 +571,17 @@ static ssize_t write_kmem(struct file * file, const char __user * buf,
 #endif
 
 #ifdef CONFIG_DEVPORT
-static ssize_t read_port(struct file * file, char __user * buf,
+static ssize_t read_port(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
 {
         unsigned long i = *ppos;
         char __user *tmp = buf;
 
         if (!access_ok(VERIFY_WRITE, buf, count))
-                return -EFAULT; 
+                return -EFAULT;
         while (count-- > 0 && i < 65536) {
-                if (__put_user(inb(i),tmp) < 0) 
-                        return -EFAULT;  
+                if (__put_user(inb(i), tmp) < 0)
+                        return -EFAULT;
                 i++;
                 tmp++;
         }
@@ -588,22 +589,22 @@ static ssize_t read_port(struct file * file, char __user * buf,
         return tmp-buf;
 }
 
-static ssize_t write_port(struct file * file, const char __user * buf,
+static ssize_t write_port(struct file *file, const char __user *buf,
                           size_t count, loff_t *ppos)
 {
         unsigned long i = *ppos;
         const char __user * tmp = buf;
 
-        if (!access_ok(VERIFY_READ,buf,count))
+        if (!access_ok(VERIFY_READ, buf, count))
                 return -EFAULT;
         while (count-- > 0 && i < 65536) {
                 char c;
                 if (__get_user(c, tmp)) {
                         if (tmp > buf)
                                 break;
-                        return -EFAULT; 
+                        return -EFAULT;
                 }
-                outb(c,i);
+                outb(c, i);
                 i++;
                 tmp++;
         }
@@ -612,13 +613,13 @@ static ssize_t write_port(struct file * file, const char __user * buf,
 }
 #endif
 
-static ssize_t read_null(struct file * file, char __user * buf,
+static ssize_t read_null(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
 {
         return 0;
 }
 
-static ssize_t write_null(struct file * file, const char __user * buf,
+static ssize_t write_null(struct file *file, const char __user *buf,
                           size_t count, loff_t *ppos)
 {
         return count;
@@ -630,13 +631,13 @@ static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
         return sd->len;
 }
 
-static ssize_t splice_write_null(struct pipe_inode_info *pipe,struct file *out,
+static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
                                  loff_t *ppos, size_t len, unsigned int flags)
 {
         return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 }
 
-static ssize_t read_zero(struct file * file, char __user * buf, 
+static ssize_t read_zero(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
 {
         size_t written;
@@ -667,7 +668,7 @@ static ssize_t read_zero(struct file * file, char __user * buf,
         return written ? written : -EFAULT;
 }
 
-static int mmap_zero(struct file * file, struct vm_area_struct * vma)
+static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 {
 #ifndef CONFIG_MMU
         return -ENOSYS;
@@ -677,7 +678,7 @@ static int mmap_zero(struct file * file, struct vm_area_struct * vma)
         return 0;
 }
 
-static ssize_t write_full(struct file * file, const char __user * buf,
+static ssize_t write_full(struct file *file, const char __user *buf,
                           size_t count, loff_t *ppos)
 {
         return -ENOSPC;
@@ -688,8 +689,7 @@ static ssize_t write_full(struct file * file, const char __user * buf,
  * can fopen() both devices with "a" now.  This was previously impossible.
  * -- SRB.
  */
-
-static loff_t null_lseek(struct file * file, loff_t offset, int orig)
+static loff_t null_lseek(struct file *file, loff_t offset, int orig)
 {
         return file->f_pos = 0;
 }
@@ -702,24 +702,31 @@ static loff_t null_lseek(struct file * file, loff_t offset, int orig)
  * also note that seeking relative to the "end of file" isn't supported:
  * it has no meaning, so it returns -EINVAL.
  */
-static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
+static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 {
         loff_t ret;
 
         mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
         switch (orig) {
-                case 0:
-                        file->f_pos = offset;
-                        ret = file->f_pos;
-                        force_successful_syscall_return();
+        case SEEK_CUR:
+                offset += file->f_pos;
+                if ((unsigned long long)offset <
+                    (unsigned long long)file->f_pos) {
+                        ret = -EOVERFLOW;
                         break;
-                case 1:
-                        file->f_pos += offset;
-                        ret = file->f_pos;
-                        force_successful_syscall_return();
+                }
+        case SEEK_SET:
+                /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
+                if ((unsigned long long)offset >= ~0xFFFULL) {
+                        ret = -EOVERFLOW;
                         break;
-                default:
-                        ret = -EINVAL;
+                }
+                file->f_pos = offset;
+                ret = file->f_pos;
+                force_successful_syscall_return();
+                break;
+        default:
+                ret = -EINVAL;
         }
         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
         return ret;
@@ -803,7 +810,7 @@ static const struct file_operations oldmem_fops = {
 };
 #endif
 
-static ssize_t kmsg_write(struct file * file, const char __user * buf,
+static ssize_t kmsg_write(struct file *file, const char __user *buf,
                           size_t count, loff_t *ppos)
 {
         char *tmp;
@@ -825,7 +832,7 @@ static ssize_t kmsg_write(struct file * file, const char __user * buf,
 }
 
 static const struct file_operations kmsg_fops = {
-        .write =        kmsg_write,
+        .write = kmsg_write,
 };
 
 static const struct memdev {
@@ -876,7 +883,7 @@ static int memory_open(struct inode *inode, struct file *filp)
 }
 
 static const struct file_operations memory_fops = {
-        .open           = memory_open,
+        .open = memory_open,
 };
 
 static char *mem_devnode(struct device *dev, mode_t *mode)
@@ -897,7 +904,7 @@ static int __init chr_dev_init(void)
         if (err)
                 return err;
 
-        if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
+        if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 
         mem_class = class_create(THIS_MODULE, "mem");
diff --git a/drivers/char/mmtimer.c b/drivers/char/mmtimer.c
index 918711aa56f3..04fd0d843b3b 100644
--- a/drivers/char/mmtimer.c
+++ b/drivers/char/mmtimer.c
@@ -546,7 +546,7 @@ static void mmtimer_tasklet(unsigned long data)
 {
         int nodeid = data;
         struct mmtimer_node *mn = &timers[nodeid];
-        struct mmtimer *x = rb_entry(mn->next, struct mmtimer, list);
+        struct mmtimer *x;
         struct k_itimer *t;
         unsigned long flags;
 
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index 2e50f4dfc79c..bdae8327143c 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -48,6 +48,7 @@
 #include <linux/audit.h>
 #include <linux/file.h>
 #include <linux/uaccess.h>
+#include <linux/module.h>
 
 #include <asm/system.h>
 
@@ -2091,3 +2092,19 @@ struct tty_ldisc_ops tty_ldisc_N_TTY = {
         .receive_buf     = n_tty_receive_buf,
         .write_wakeup    = n_tty_write_wakeup
 };
+
+/**
+ *      n_tty_inherit_ops       -       inherit N_TTY methods
+ *      @ops: struct tty_ldisc_ops where to save N_TTY methods
+ *
+ *      Used by a generic struct tty_ldisc_ops to easily inherit N_TTY
+ *      methods.
+ */
+
+void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
+{
+        *ops = tty_ldisc_N_TTY;
+        ops->owner = NULL;
+        ops->refcount = ops->flags = 0;
+}
+EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
diff --git a/drivers/char/tty_audit.c b/drivers/char/tty_audit.c
index ac16fbec72d0..283a15bc84e3 100644
--- a/drivers/char/tty_audit.c
+++ b/drivers/char/tty_audit.c
@@ -148,7 +148,6 @@ void tty_audit_fork(struct signal_struct *sig)
         spin_lock_irq(&current->sighand->siglock);
         sig->audit_tty = current->signal->audit_tty;
         spin_unlock_irq(&current->sighand->siglock);
-        sig->tty_audit_buf = NULL;
 }
 
 /**