linux/ipc, branch v3.16

ipc: convert use of typedef ctl_table to struct ctl_table

2014-06-06T23:08:16Z

This typedef is unnecessary and should just be removed. Signed-off-by: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc/sem.c: add a printk_once for semctl(GETNCNT/GETZCNT)

2014-06-06T23:08:15Z

The actual Linux implementation for semctl(GETNCNT) and semctl(GETZCNT) always (since 0.99.10) reported a thread as sleeping on all semaphores that are listed in the semop() call. The documented behavior (both in the Linux man page and in the Single Unix Specification) is that a task should be reported on exactly one semaphore: The semaphore that caused the thread to got to sleep. This patch adds a pr_info_once() that is triggered if a thread hits the relevant case. The code triggers slightly too often, otherwise it would be necessary to replicate the old code. As there are no known users of GETNCNT or GETZCNT, this is done to prevent unnecessary bloat. The task that triggered is reported with name (tsk->comm) and pid. Signed-off-by: Manfred Spraul Acked-by: Davidlohr Bueso Cc: Michael Kerrisk Cc: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc/sem.c: make semctl(,,{GETNCNT,GETZCNT}) standard compliant

2014-06-06T23:08:15Z

SUSv4 clearly defines how semncnt and semzcnt must be calculated: A task waits on exactly one semaphore: The semaphore from the first operation in the sop array that cannot proceed. The Linux implementation never followed the standard, it tried to count all semaphores that might be the reason why a task sleeps. This patch fixes that. Note: a) The implementation assumes that GETNCNT and GETZCNT are rare operations, therefore the code counts them only on demand. (If they wouldn't be rare, then the non-compliance would have been found earlier) b) compared to the initial version of the patch, the BUG_ONs were removed and it was clarified that the new behavior conforms to SUS. Back-compatibility concerns: Manfred: : - there is no application in Fedora that uses GETNCNT or GETZCNT. : : - application that use only single-sop semop() are also safe, the : difference only affects complex apps. : : - portable application are also safe, the new behavior is standard : compliant. : : But that's it. The old behavior existed in Linux from 0.99.something : until now. Michael: : * These operations seem to be very little used. Grepping the public : source that is contained Fedora 20 source DVD, there appear to be no : uses. Of course, this says nothing about uses in private / : non-mainstream FOSS code, but it seems likely that the same pattern : is followed there. : : * The existing behavior is hard enough to understand that I suspect : that no one understood it well enough to rely on it anyway : (especially as that behavior contradicted both man page and POSIX). : : So, there's a chance of breakage, but I estimate that it's minute. Signed-off-by: Manfred Spraul Cc: Davidlohr Bueso Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc/sem.c: store which operation blocks in perform_atomic_semop()

2014-06-06T23:08:15Z

Preparation for the next patch: In the slow-path of perform_atomic_semop(), store a pointer to the operation that caused the operation to block. Signed-off-by: Manfred Spraul Cc: Davidlohr Bueso Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc/sem.c: change perform_atomic_semop parameters

2014-06-06T23:08:15Z

Right now, perform_atomic_semop gets the content of sem_queue as individual fields. Changes that, instead pass a pointer to sem_queue. This is a preparation for the next patch: it uses sem_queue to store the reason why a task must sleep. Signed-off-by: Manfred Spraul Cc: Davidlohr Bueso Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc/sem.c: remove code duplication

2014-06-06T23:08:15Z

count_semzcnt and count_semncnt are more of less identical. The patch creates a single function that either counts the number of tasks waiting for zero or waiting due to a decrease operation. Compared to the initial version, the BUG_ONs were removed. Signed-off-by: Manfred Spraul Cc: Davidlohr Bueso Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc/sem.c: bugfix for semctl(,,GETZCNT)

2014-06-06T23:08:15Z

GETZCNT is supposed to return the number of threads that wait until a semaphore value becomes 0. The current implementation overlooks complex operations that contain both wait-for-zero operation and operations that alter at least one semaphore. The patch fixes that. It's intentionally copy&paste, this will be cleaned up in the next patch. Signed-off-by: Manfred Spraul Cc: Davidlohr Bueso Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc,msg: document volatile r_msg

2014-06-06T23:08:15Z

The need for volatile is not obvious, document it. Signed-off-by: Davidlohr Bueso Signed-off-by: Manfred Spraul Cc: Aswin Chandramouleeswaran Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc,msg: move some msgq ns code around

2014-06-06T23:08:14Z

Nothing big and no logical changes, just get rid of some redundant function declarations. Move msg_[init/exit]_ns down the end of the file. Signed-off-by: Davidlohr Bueso Signed-off-by: Manfred Spraul Cc: Aswin Chandramouleeswaran Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc,msg: use current->state helpers

2014-06-06T23:08:14Z

Call __set_current_state() instead of assigning the new state directly. Signed-off-by: Davidlohr Bueso Signed-off-by: Manfred Spraul Cc: Aswin Chandramouleeswaran Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds