With the introduction of the new unified work queue thread pools, we lost one feature: It's no longer possible to know which worker is causing the CPU to wake out of idle. The result is that PowerTOP now reports a lot of "kworker/a:b" instead of more readable results. This patch adds a pair of tracepoints to the new workqueue code, similar in style to the timer/hrtimer tracepoints. With this pair of tracepoints, the next PowerTOP can correctly report which work item caused the wakeup (and how long it took): Interrupt (43) i915 time 3.51ms wakeups 141 Work ieee80211_iface_work time 0.81ms wakeups 29 Work do_dbs_timer time 0.55ms wakeups 24 Process Xorg time 21.36ms wakeups 4 Timer sched_rt_period_timer time 0.01ms wakeups 1 Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's a really simple list, and several of the users want to go backwards in it to find the previous vma. So rather than have to look up the previous entry with 'find_vma_prev()' or something similar, just make it doubly linked instead. Tested-by: Ian Campbell <ijc@hellion.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kfifo_skip() is currently broken, due to the missing of the internal helper function. Add it. Signed-off-by: Andrea Righi <arighi@develer.com> Cc: Greg KH <greg@kroah.com> Acked-by: Stefani Seibold <stefani@seibold.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: fs: brlock vfsmount_lock fs: scale files_lock lglock: introduce special lglock and brlock spin locks tty: fix fu_list abuse fs: cleanup files_lock locking fs: remove extra lookup in __lookup_hash fs: fs_struct rwlock to spinlock apparmor: use task path helpers fs: dentry allocation consolidation fs: fix do_lookup false negative mbcache: Limit the maximum number of cache entries hostfs ->follow_link() braino hostfs: dumb (and usually harmless) tpyo - strncpy instead of strlcpy remove SWRITE* I/O types kill BH_Ordered flag vfs: update ctime when changing the file's permission by setfacl cramfs: only unlock new inodes fix reiserfs_evict_inode end_writeback second call
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: perf tools: Fix build on POSIX shells latencytop: Fix kconfig dependency warnings perf annotate tui: Fix exit and RIGHT keys handling tracing: Sanitize value returned from write(trace_marker, "...", len) tracing/events: Convert format output to seq_file tracing: Extend recordmcount to better support Blackfin mcount tracing: Fix ring_buffer_read_page reading out of page boundary tracing: Fix an unallocated memory access in function_graph
fs: fs_struct rwlock to spinlock struct fs_struct.lock is an rwlock with the read-side used to protect root and pwd members while taking references to them. Taking a reference to a path typically requires just 2 atomic ops, so the critical section is very small. Parallel read-side operations would have cacheline contention on the lock, the dentry, and the vfsmount cachelines, so the rwlock is unlikely to ever give a real parallelism increase. Replace it with a spinlock to avoid one or two atomic operations in typical path lookup fastpath. Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb: vt,console,kdb: preserve console_blanked while in kdb vt: fix regression warnings from KMS merge arm,kgdb: fix GDB_MAX_REGS no longer used kgdb: add missing __percpu markup in arch/x86/kernel/kgdb.c kdb: fix compile error without CONFIG_KALLSYMS
Using a program like the following:
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main() {
id_t id;
siginfo_t infop;
pid_t res;
id = fork();
if (id == 0) { sleep(1); exit(0); }
kill(id, SIGSTOP);
alarm(1);
waitid(P_PID, id, &infop, WCONTINUED);
return 0;
}
to call waitid() on a stopped process results in access to the child task's
credentials without the RCU read lock being held - which may be replaced in the
meantime - eliciting the following warning:
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
kernel/exit.c:1460 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
2 locks held by waitid02/22252:
#0: (tasklist_lock){.?.?..}, at: [<ffffffff81061ce5>] do_wait+0xc5/0x310
#1: (&(&sighand->siglock)->rlock){-.-...}, at: [<ffffffff810611da>]
wait_consider_task+0x19a/0xbe0
stack backtrace:
Pid: 22252, comm: waitid02 Not tainted 2.6.35-323cd+ #3
Call Trace:
[<ffffffff81095da4>] lockdep_rcu_dereference+0xa4/0xc0
[<ffffffff81061b31>] wait_consider_task+0xaf1/0xbe0
[<ffffffff81061d15>] do_wait+0xf5/0x310
[<ffffffff810620b6>] sys_waitid+0x86/0x1f0
[<ffffffff8105fce0>] ? child_wait_callback+0x0/0x70
[<ffffffff81003282>] system_call_fastpath+0x16/0x1b
This is fixed by holding the RCU read lock in wait_task_continued() to ensure
that the task's current credentials aren't destroyed between us reading the
cred pointer and us reading the UID from those credentials.
Furthermore, protect wait_task_stopped() in the same way.
We don't need to keep holding the RCU read lock once we've read the UID from
the credentials as holding the RCU read lock doesn't stop the target task from
changing its creds under us - so the credentials may be outdated immediately
after we've read the pointer, lock or no lock.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make do_execve() take a const filename pointer so that kernel_execve() compiles correctly on ARM: arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type This also requires the argv and envp arguments to be consted twice, once for the pointer array and once for the strings the array points to. This is because do_execve() passes a pointer to the filename (now const) to copy_strings_kernel(). A simpler alternative would be to cast the filename pointer in do_execve() when it's passed to copy_strings_kernel(). do_execve() may not change any of the strings it is passed as part of the argv or envp lists as they are some of them in .rodata, so marking these strings as const should be fine. Further kernel_execve() and sys_execve() need to be changed to match. This has been test built on x86_64, frv, arm and mips. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If CONFIG_KGDB_KDB is set and CONFIG_KALLSYMS is not set the kernel will fail to build with the error: kernel/built-in.o: In function `kallsyms_symbol_next': kernel/debug/kdb/kdb_support.c:237: undefined reference to `kdb_walk_kallsyms' kernel/built-in.o: In function `kallsyms_symbol_complete': kernel/debug/kdb/kdb_support.c:193: undefined reference to `kdb_walk_kallsyms' The kdb_walk_kallsyms needs a #ifdef proper header to match the C implementation. This patch also fixes the compiler warnings in kdb_support.c when compiling without CONFIG_KALLSYMS set. The compiler warnings are a result of the kallsyms_lookup() macro not initializing the two of the pass by reference variables. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Reported-by: Michal Simek <monstr@monstr.eu>