diff options
| -rw-r--r-- | lib/libc/gen/sem_init.3 | 27 |
1 files changed, 9 insertions, 18 deletions
diff --git a/lib/libc/gen/sem_init.3 b/lib/libc/gen/sem_init.3 index d765a574e67b7..202612a364913 100644 --- a/lib/libc/gen/sem_init.3 +++ b/lib/libc/gen/sem_init.3 @@ -27,7 +27,7 @@ .\" .\" $FreeBSD$ .\" -.Dd February 15, 2000 +.Dd December 8, 2009 .Dt SEM_INIT 3 .Os .Sh NAME @@ -48,8 +48,7 @@ to have the value .Fa value . A non-zero value for .Fa pshared -specifies a shared semaphore that can be used by multiple processes, which this -implementation is not capable of. +specifies a shared semaphore that can be used by multiple processes. .Pp Following a successful call to .Fn sem_init , @@ -78,8 +77,6 @@ argument exceeds .Dv SEM_VALUE_MAX . .It Bq Er ENOSPC Memory allocation error. -.It Bq Er EPERM -Unable to initialize a shared semaphore. .El .Sh SEE ALSO .Xr sem_destroy 3 , @@ -93,16 +90,10 @@ The .Fn sem_init function conforms to .St -p1003.1-96 . -.Pp -This implementation does not support shared semaphores, and reports this fact -by setting -.Va errno -to -.Er EPERM . -This is perhaps a stretch of the intention of -.Tn POSIX , -but is -compliant, with the caveat that -.Fn sem_init -always reports a permissions error when an attempt to create a shared semaphore -is made. +.Sh BUGS +A sem_t is a pointer to a separately allocated structure, +therefore process shared semaphores only work between related processes +and do not perform very well +(each operation is a system call, +while single-process semaphores only do a system call +if they need to block or wake up a thread). |