Hi Dave, On 5/12/20 6:36 PM, Dave Martin wrote: > The prctl list has historically been sorted by prctl name (ignoring > any SET_ or GET_ prefix) to make individual prctls easier to find. > Some noise seems to have crept in since. > > Sort the list back into order. Similarly, reorder the list of > prctls specified to return non-zero values on success. This is a good patch. But see my comments on patch 04. I'd prefer a patch like this at the end of a series, rather than in the middle of it. > Content movement only. No semantic change. And explicitly noting that detail is very helpful to me. Patch applied. Cheers, Michael > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> > --- > man2/prctl.2 | 138 +++++++++++++++++++++++++++++------------------------------ > 1 file changed, 69 insertions(+), 69 deletions(-) > > diff --git a/man2/prctl.2 b/man2/prctl.2 > index e5b2b4b..1611448 100644 > --- a/man2/prctl.2 > +++ b/man2/prctl.2 > @@ -490,6 +490,52 @@ Pass \fBPR_FP_EXC_SW_ENABLE\fP to use FPEXC for FP exception enables, > Return floating-point exception mode, > in the location pointed to by > .IR "(int\ *) arg2" . > +.\" prctl PR_SET_IO_FLUSHER > +.TP > +.BR PR_SET_IO_FLUSHER " (since Linux 5.6)" > +If a user process is involved in the block layer or filesystem I/O path, > +and can allocate memory while processing I/O requests it must set > +\fIarg2\fP to 1. > +This will put the process in the IO_FLUSHER state, > +which allows it special treatment to make progress when allocating memory. > +If \fIarg2\fP is 0, the process will clear the IO_FLUSHER state, and > +the default behavior will be used. > +.IP > +The calling process must have the > +.BR CAP_SYS_RESOURCE > +capability. > +.IP > +.IR arg3 , > +.IR arg4 , > +and > +.IR arg5 > +must be zero. > +.IP > +The IO_FLUSHER state is inherited by a child process created via > +.BR fork (2) > +and is preserved across > +.BR execve (2). > +.IP > +Examples of IO_FLUSHER applications are FUSE daemons, SCSI device > +emulation daemons, and daemons that perform error handling like multipath > +path recovery applications. > +.\" prctl PR_GET_IO_FLUSHER > +.TP > +.B PR_GET_IO_FLUSHER (Since Linux 5.6) > +Return (as the function result) the IO_FLUSHER state of the caller. > +A value of 1 indicates that the caller is in the IO_FLUSHER state; > +0 indicates that the caller is not in the IO_FLUSHER state. > +.IP > +The calling process must have the > +.BR CAP_SYS_RESOURCE > +capability. > +.IP > +.IR arg2 , > +.IR arg3 , > +.IR arg4 , > +and > +.IR arg5 > +must be zero. > .\" prctl PR_SET_KEEPCAPS > .TP > .BR PR_SET_KEEPCAPS " (since Linux 2.2.18)" > @@ -1207,23 +1253,6 @@ call failing with the error > .BR ENXIO . > For further details, see the kernel source file > .IR Documentation/admin-guide/kernel-parameters.txt . > -.\" prctl PR_SET_THP_DISABLE > -.TP > -.BR PR_SET_THP_DISABLE " (since Linux 3.15)" > -.\" commit a0715cc22601e8830ace98366c0c2bd8da52af52 > -Set the state of the "THP disable" flag for the calling thread. > -If > -.I arg2 > -has a nonzero value, the flag is set, otherwise it is cleared. > -Setting this flag provides a method > -for disabling transparent huge pages > -for jobs where the code cannot be modified, and using a malloc hook with > -.BR madvise (2) > -is not an option (i.e., statically allocated data). > -The setting of the "THP disable" flag is inherited by a child created via > -.BR fork (2) > -and is preserved across > -.BR execve (2). > .\" > .\" prctl PR_TASK_PERF_EVENTS_DISABLE > .TP > @@ -1256,6 +1285,23 @@ renamed > .\" commit cdd6c482c9ff9c55475ee7392ec8f672eddb7be6 > in Linux 2.6.32. > .\" > +.\" prctl PR_SET_THP_DISABLE > +.TP > +.BR PR_SET_THP_DISABLE " (since Linux 3.15)" > +.\" commit a0715cc22601e8830ace98366c0c2bd8da52af52 > +Set the state of the "THP disable" flag for the calling thread. > +If > +.I arg2 > +has a nonzero value, the flag is set, otherwise it is cleared. > +Setting this flag provides a method > +for disabling transparent huge pages > +for jobs where the code cannot be modified, and using a malloc hook with > +.BR madvise (2) > +is not an option (i.e., statically allocated data). > +The setting of the "THP disable" flag is inherited by a child created via > +.BR fork (2) > +and is preserved across > +.BR execve (2). > .\" prctl PR_GET_THP_DISABLE > .TP > .BR PR_GET_THP_DISABLE " (since Linux 3.15)" > @@ -1438,67 +1484,21 @@ system call on Tru64). > for information on versions and architectures.) > Return unaligned access control bits, in the location pointed to by > .IR "(unsigned int\ *) arg2" . > -.\" prctl PR_SET_IO_FLUSHER > -.TP > -.BR PR_SET_IO_FLUSHER " (since Linux 5.6)" > -If a user process is involved in the block layer or filesystem I/O path, > -and can allocate memory while processing I/O requests it must set > -\fIarg2\fP to 1. > -This will put the process in the IO_FLUSHER state, > -which allows it special treatment to make progress when allocating memory. > -If \fIarg2\fP is 0, the process will clear the IO_FLUSHER state, and > -the default behavior will be used. > -.IP > -The calling process must have the > -.BR CAP_SYS_RESOURCE > -capability. > -.IP > -.IR arg3 , > -.IR arg4 , > -and > -.IR arg5 > -must be zero. > -.IP > -The IO_FLUSHER state is inherited by a child process created via > -.BR fork (2) > -and is preserved across > -.BR execve (2). > -.IP > -Examples of IO_FLUSHER applications are FUSE daemons, SCSI device > -emulation daemons, and daemons that perform error handling like multipath > -path recovery applications. > -.\" prctl PR_GET_IO_FLUSHER > -.TP > -.B PR_GET_IO_FLUSHER (Since Linux 5.6) > -Return (as the function result) the IO_FLUSHER state of the caller. > -A value of 1 indicates that the caller is in the IO_FLUSHER state; > -0 indicates that the caller is not in the IO_FLUSHER state. > -.IP > -The calling process must have the > -.BR CAP_SYS_RESOURCE > -capability. > -.IP > -.IR arg2 , > -.IR arg3 , > -.IR arg4 , > -and > -.IR arg5 > -must be zero. > .SH RETURN VALUE > On success, > +.BR PR_CAP_AMBIENT + PR_CAP_AMBIENT_IS_SET , > +.BR PR_CAPBSET_READ , > .BR PR_GET_DUMPABLE , > .BR PR_GET_FP_MODE , > +.BR PR_GET_IO_FLUSHER , > .BR PR_GET_KEEPCAPS , > +.BR PR_MCE_KILL_GET , > .BR PR_GET_NO_NEW_PRIVS , > +.BR PR_GET_SECUREBITS , > +.BR PR_GET_SPECULATION_CTRL , > .BR PR_GET_THP_DISABLE , > -.BR PR_CAPBSET_READ , > .BR PR_GET_TIMING , > .BR PR_GET_TIMERSLACK , > -.BR PR_GET_SECUREBITS , > -.BR PR_GET_SPECULATION_CTRL , > -.BR PR_MCE_KILL_GET , > -.BR PR_CAP_AMBIENT + PR_CAP_AMBIENT_IS_SET , > -.BR PR_GET_IO_FLUSHER , > and (if it returns) > .BR PR_GET_SECCOMP > return the nonnegative values described above. > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
