Optimized ARM RWSEM algorithm
Add new, lookup3-based jhash. See: http://burtleburtle.net/bob/hash/doobs.html

Signed-off-by: Andika Edo <dhiika@phiexz.com>
pids: fix a race in pid generation that causes pids to be reused immediately

A program that repeatedly forks and waits is susceptible to having the
same pid repeated, especially when it competes with another instance of
the same program.  This is really bad for bash implementation.
Furthermore, many shell scripts assume that pid numbers will not be used
for some length of time.

Race Description:

A                                    B

// pid == offset == n                // pid == offset == n + 1
test_and_set_bit(offset, map->page)
									 test_and_set_bit(offset, map->page);
									 pid_ns->last_pid = pid;
pid_ns->last_pid = pid;
									 // pid == n + 1 is freed (wait())

									 // Next fork()...
									 last = pid_ns->last_pid; // == n
									 pid = last + 1;

Code to reproduce it (Running multiple instances is more effective):

#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

// The distance mod 32768 between two pids, where the first pid is expected
// to be smaller than the second.
int PidDistance(pid_t first, pid_t second) {
  return (second + 32768 - first) % 32768;
}

int main(int argc, char* argv[]) {
  int failed = 0;
  pid_t last_pid = 0;
  int i;
  printf("%d\n", sizeof(pid_t));
  for (i = 0; i < 10000000; ++i) {
	if (i % 32786 == 0)
	  printf("Iter: %d\n", i/32768);
	int child_exit_code = i % 256;
	pid_t pid = fork();
	if (pid == -1) {
	  fprintf(stderr, "fork failed, iteration %d, errno=%d", i, errno);
	  exit(1);
	}
	if (pid == 0) {
	  // Child
	  exit(child_exit_code);
	} else {
	  // Parent
	  if (i > 0) {
		int distance = PidDistance(last_pid, pid);
		if (distance == 0 || distance > 30000) {
		  fprintf(stderr,
				  "Unexpected pid sequence: previous fork: pid=%d, "
				  "current fork: pid=%d for iteration=%d.\n",
				  last_pid, pid, i);
		  failed = 1;
		}
	  }
	  last_pid = pid;
	  int status;
	  int reaped = wait(&status);
	  if (reaped != pid) {
		fprintf(stderr,
				"Wait return value: expected pid=%d, "
				"got %d, iteration %d\n",
				pid, reaped, i);
		failed = 1;
	  } else if (WEXITSTATUS(status) != child_exit_code) {
		fprintf(stderr,
				"Unexpected exit status %x, iteration %d\n",
				WEXITSTATUS(status), i);
		failed = 1;
	  }
	}
  }
  exit(failed);
}

Thanks to Ted Tso for the key ideas of this implementation.

Signed-off-by: Salman Qazi <sqazi@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andika Edo <dhiika@phiexz.com>
lib: Improve the performance of memcpy and memmove of the general version

The performance of memcpy and memmove of the general version is
very inefficient, this patch improves them.
lib: Introduce some memory copy macros and functions
The kernel's memcpy and memmove is very inefficient. But the glibc version is
quite fast, in some cases it is 10 times faster than the kernel version. So I
introduce some memory copy macros and functions of the glibc to improve the
kernel version's performance.

The strategy of the memory functions is:
1. Copy bytes until the destination pointer is aligned.
2. Copy words in unrolled loops. If the source and destination are not aligned
   in the same way, use word memory operations, but shift and merge two read
   words before writing.
3. Copy the few remaining bytes.
net/ipv4: Eliminate kstrdup memory leak
The string clone is only used as a temporary copy of the argument val
within the while loop, and so it should be freed before leaving the
function.  The call to strsep, however, modifies clone, so a pointer to the
front of the string is kept in saved_clone, to make it possible to free it.

The sematic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
local idexpression x;
expression E;
identifier l;
statement S;
@@

*x= \(kasprintf\|kstrdup\)(...);
...
if (x == NULL) S
... when != kfree(x)
	when != E = x
if (...) {
  <... when != kfree(x)
* goto l;
  ...>
* return ...;
}
// </smpl>
Fix atomic functions in bfq