diff options
Diffstat (limited to 'man2/semop.2')
| -rw-r--r-- | man2/semop.2 | 44 |
1 files changed, 22 insertions, 22 deletions
diff --git a/man2/semop.2 b/man2/semop.2 index ece7a0e..b04fe6a 100644 --- a/man2/semop.2 +++ b/man2/semop.2 @@ -12,7 +12,7 @@ .\" 2005-04-08, mtk, Noted kernel version numbers for semtimedop() .\" 2007-07-09, mtk, Added an EXAMPLE code segment. .\" -.TH semop 2 2023-05-03 "Linux man-pages 6.05.01" +.TH semop 2 2023-10-31 "Linux man-pages 6.7" .SH NAME semop, semtimedop \- System V semaphore operations .SH LIBRARY @@ -21,17 +21,17 @@ Standard C library .SH SYNOPSIS .nf .B #include <sys/sem.h> -.PP +.P .BI "int semop(int " semid ", struct sembuf *" sops ", size_t " nsops ); .BI "int semtimedop(int " semid ", struct sembuf *" sops ", size_t " nsops , .BI " const struct timespec *_Nullable " timeout ); .fi -.PP +.P .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE -.PP +.P .BR semtimedop (): .nf _GNU_SOURCE @@ -39,7 +39,7 @@ Feature Test Macro Requirements for glibc (see .SH DESCRIPTION Each semaphore in a System\ V semaphore set has the following associated values: -.PP +.P .in +4n .EX unsigned short semval; /* semaphore value */ @@ -49,7 +49,7 @@ pid_t sempid; /* PID of process that last modified the semaphore value */ .EE .in -.PP +.P .BR semop () performs operations on selected semaphores in the set indicated by .IR semid . @@ -62,7 +62,7 @@ specifies an operation to be performed on a single semaphore. The elements of this structure are of type .IR "struct sembuf" , containing the following members: -.PP +.P .in +4n .EX unsigned short sem_num; /* semaphore number */ @@ -70,7 +70,7 @@ short sem_op; /* semaphore operation */ short sem_flg; /* operation flags */ .EE .in -.PP +.P Flags recognized in .I sem_flg are @@ -80,7 +80,7 @@ and If an operation specifies .BR SEM_UNDO , it will be automatically undone when the process terminates. -.PP +.P The set of operations contained in .I sops is performed in @@ -95,14 +95,14 @@ performed immediately depends on the presence of the flag in the individual .I sem_flg fields, as noted below. -.PP +.P Each operation is performed on the .IR sem_num \-th semaphore of the semaphore set, where the first semaphore of the set is numbered 0. There are three types of operation, distinguished by the value of .IR sem_op . -.PP +.P If .I sem_op is a positive integer, the operation adds this value to @@ -117,7 +117,7 @@ from the semaphore adjustment value for this semaphore. This operation can always proceed\[em]it never forces a thread to wait. The calling process must have alter permission on the semaphore set. -.PP +.P If .I sem_op is zero, the process must have read permission on the semaphore @@ -165,7 +165,7 @@ fails, with .I errno set to .BR EINTR . -.PP +.P If .I sem_op is less than zero, the process must have alter permission on the @@ -229,7 +229,7 @@ fails, with .I errno set to .BR EINTR . -.PP +.P On successful completion, the .I sempid value for each semaphore specified in the array pointed to by @@ -270,7 +270,7 @@ then .BR semtimedop () behaves exactly like .BR semop (). -.PP +.P Note that if .BR semtimedop () is interrupted by a signal, causing the call to fail with the error @@ -370,13 +370,13 @@ structures of a process aren't inherited by the child produced by but they are inherited across an .BR execve (2) system call. -.PP +.P .BR semop () is never automatically restarted after being interrupted by a signal handler, regardless of the setting of the .B SA_RESTART flag when establishing a signal handler. -.PP +.P A semaphore adjustment .RI ( semadj ) value is a per-process, per-semaphore integer that is the negated sum @@ -409,7 +409,7 @@ flag allows more than one process to share a list; see .BR clone (2) for details. -.PP +.P The \fIsemval\fP, \fIsempid\fP, \fIsemzcnt\fP, and \fIsemnct\fP values for a semaphore can all be retrieved using appropriate .BR semctl (2) @@ -443,7 +443,7 @@ array. Maximum allowable value for .IR semval : implementation dependent (32767). -.PP +.P The implementation has no intrinsic limits for the adjust on exit maximum value .RB ( SEMAEM ), @@ -471,7 +471,7 @@ is specified for a semaphore operation). Linux adopts a third approach: decreasing the semaphore value as far as possible (i.e., to zero) and allowing process termination to proceed immediately. -.PP +.P In Linux 2.6.x, x <= 10, there is a bug that in some circumstances prevents a thread that is waiting for a semaphore value to become zero from being woken up when the value does actually become zero. @@ -485,7 +485,7 @@ The following code segment uses .BR semop () to atomically wait for the value of semaphore 0 to become zero, and then increment the semaphore value by one. -.PP +.P .in +4n .EX struct sembuf sops[2]; @@ -507,7 +507,7 @@ if (semop(semid, sops, 2) == \-1) { } .EE .in -.PP +.P A further example of the use of .BR semop () can be found in |