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| author | Alejandro Colomar <alx@kernel.org> | 2025-05-30 01:17:50 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2025-05-30 14:44:35 +0200 |
| commit | e8b597ea7957a3ad0de84a675b129b5c0ce94794 (patch) | |
| tree | de0bcd73634a1f8f18bb910e6ec7d39268f5ea34 | |
| parent | e0db144da7ed030fd29a83b83f13789b008ac357 (diff) | |
| download | man-pages-e8b597ea7957a3ad0de84a675b129b5c0ce94794.tar.gz | |
man/man2/futex.2: Tweak after making sashimi of this page
Signed-off-by: Alejandro Colomar <alx@kernel.org>
| -rw-r--r-- | man/man2/futex.2 | 67 |
1 files changed, 12 insertions, 55 deletions
diff --git a/man/man2/futex.2 b/man/man2/futex.2 index 6e99f6eec2..69df4036ad 100644 --- a/man/man2/futex.2 +++ b/man/man2/futex.2 @@ -23,11 +23,7 @@ Standard C library .BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */" .B #include <unistd.h> .P -.BI "long syscall(SYS_futex, uint32_t *" uaddr ", int " futex_op \ -", uint32_t " val , -.BI " const struct timespec *" timeout \ -", \f[R]/* or:\f[] uint32_t " val2 " \f[R]*/\f[]" -.BI " uint32_t *" uaddr2 ", uint32_t " val3 ); +.BI "long syscall(SYS_futex, uint32_t *" uaddr ", int " op ", ...);" .fi .SH DESCRIPTION The @@ -144,58 +140,20 @@ argument points to the futex word. On all platforms, futexes are four-byte integers that must be aligned on a four-byte boundary. The operation to perform on the futex is specified in the -.I futex_op -argument; -.I val -is a value whose meaning and purpose depends on -.IR futex_op . -.P -The remaining arguments -.RI ( timeout , -.IR uaddr2 , -and -.IR val3 ) -are required only for certain of the futex operations described below. -Where one of these arguments is not required, it is ignored. -.P -For several blocking operations, the -.I timeout -argument is a pointer to a -.I timespec -structure that specifies a timeout for the operation. -However, notwithstanding the prototype shown above, for some operations, -the least significant four bytes of this argument are instead -used as an integer whose meaning is determined by the operation. -For these operations, the kernel casts the -.I timeout -value first to -.IR "unsigned long", -then to -.IR uint32_t , -and in the remainder of this page, this argument is referred to as -.I val2 -when interpreted in this fashion. -.P -Where it is required, the -.I uaddr2 -argument is a pointer to a second futex word that is employed -by the operation. -.P -The interpretation of the final integer argument, -.IR val3 , -depends on the operation. +.I op +argument. .\" .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" .\" .SS Futex operations The -.I futex_op +.I op argument consists of two parts: a command that specifies the operation to be performed, bitwise ORed with zero or more options that modify the behaviour of the operation. The options that may be included in -.I futex_op +.I op are as follows: .TP .BR FUTEX_PRIVATE_FLAG " (since Linux 2.6.22)" @@ -251,7 +209,7 @@ against the clock. .P The operation specified in -.I futex_op +.I op is one of the following: .\" .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" @@ -419,7 +377,7 @@ the dead owner. .\" PI futexes. .P PI futexes are operated on by specifying one of the values listed below in -.IR futex_op . +.IR op . Note that the PI futex operations must be used as paired operations and are subject to some additional requirements: .IP \[bu] 3 @@ -443,8 +401,7 @@ This must be performed from a non-PI futex to a distinct PI futex .B EINVAL results). Additionally, -.I val -(the number of waiters to be woken) must be 1 +the number of waiters to be woken must be 1 (or the error .B EINVAL results). @@ -539,13 +496,13 @@ Invalid argument. .TP .B ENOSYS Invalid operation specified in -.IR futex_op . +.IR op . .TP .B ENOSYS The .B FUTEX_CLOCK_REALTIME option was specified in -.IR futex_op , +.IR op , but the accompanying operation was neither .BR FUTEX_WAIT_BITSET (2const), .BR FUTEX_WAIT_REQUEUE_PI (2const), @@ -625,10 +582,10 @@ Child (18535) 4 static uint32_t *futex1, *futex2, *iaddr; \& static int -futex(uint32_t *uaddr, int futex_op, uint32_t val, +futex(uint32_t *uaddr, int op, uint32_t val, const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3) { - return syscall(SYS_futex, uaddr, futex_op, val, + return syscall(SYS_futex, uaddr, op, val, timeout, uaddr2, val3); } \& |