Hi Alexander, On Tue, Mar 05, 2024 at 10:39:57AM +0300, Alexander Ofitserov wrote: > Parameter O_NONBLOCK described in man doesn't exist anymore > in kernel versions 3.13+ (particularly in commit > 3f2b9c9cdf389e303b2273679af08aab5f153517 aka v3.13-rc1~83^2~5), > which is quite old, only O_TRUNC parameter present for current kernel version, > O_NONBLOCK does nothing. > > O_NONBLOCK used in "try_stop_module" function, which is invoked by syscall > delete_module, here is the code of this function for kernel version 3.12.74: > https://elixir.bootlin.com/linux/v3.12.74/source/kernel/module.c#L775 > > However, in later kernels, this parameter disappeared. > Also, here is the code for 3.13: > https://elixir.bootlin.com/linux/v3.13/source/kernel/module.c#L767 > > In recent kernels, 6.7.5 for example, this parameter also absent: > https://elixir.bootlin.com/linux/v6.7.5/source/kernel/module/main.c#L637 > > v3 -> v4: > added more information with links to code to commit message > > v2 -> v3: > subsection Linux 3.12 and earlier renamed to O_NONBLOCK > removed info about arguments for kernels 3.12 and earlier > added semantic newlines > > v1 -> v2: > added behaviour of syscall for kernel 3.12 and earlier > in history section > added commit hash to commit message > changed word 'actual' to 'current' due to ambigious > meaning > > Signed-off-by: Alexander Ofitserov <oficerovas@xxxxxxxxxxxx> > --- > man2/delete_module.2 | 92 +++++++++++++++++++++++++------------------- > 1 file changed, 52 insertions(+), 40 deletions(-) > > diff --git a/man2/delete_module.2 b/man2/delete_module.2 > index e9c432e84..e4b107702 100644 > --- a/man2/delete_module.2 > +++ b/man2/delete_module.2 > @@ -50,42 +50,20 @@ is zero, then the module is immediately unloaded. > If a module has a nonzero reference count, > then the behavior depends on the bits set in > .IR flags . > -In normal usage (see NOTES), the > -.B O_NONBLOCK > -flag is always specified, and the > +The > .B O_TRUNC > flag may additionally be specified. > .\" O_TRUNC == KMOD_REMOVE_FORCE in kmod library > -.\" O_NONBLOCK == KMOD_REMOVE_NOWAIT in kmod library > .IP > The various combinations for "various combinations" is rather confusing, now that there's only one flag bit, right? > .I flags > have the following effect: > .RS > .TP > -.B flags == O_NONBLOCK > -The call returns immediately, with an error. > -.TP > -.B flags == (O_NONBLOCK | O_TRUNC) > +.B flags == O_TRUNC > The module is unloaded immediately, > regardless of whether it has a nonzero reference count. > -.TP > -.B (flags & O_NONBLOCK) == 0 Is flags == 0 a possibility? The rest of the page seems to say so, but this list of "various combinations" doesn't include it. > -If > -.I flags > -does not specify > -.BR O_NONBLOCK , > -the following steps occur: > .RS > -.IP \[bu] 3 > -The module is marked so that no new references are permitted. > -.IP \[bu] > -If the module's reference count is nonzero, > -the caller is placed in an uninterruptible sleep state > -.RB ( TASK_UNINTERRUPTIBLE ) > -until the reference count is zero, at which point the call unblocks. > -.IP \[bu] > -The module is unloaded in the usual way. > .RE > .RE > .P > @@ -151,11 +129,7 @@ in > .TP > .B EWOULDBLOCK > Other modules depend on this module; > -or, Please keep 'or,' in a separate line. It reduces the diff, and it doesn't hurt much. > -.B O_NONBLOCK > -was specified in > -.IR flags , > -but the reference count of this module is nonzero and > +or, the reference count of this module is nonzero and > .B O_TRUNC > was not specified in > .IR flags . > @@ -172,6 +146,54 @@ it is (before glibc 2.23) sufficient to > manually declare the interface in your code; > alternatively, you can invoke the system call using > .BR syscall (2). > +.SS O_NONBLOCK > +In Linux 3.12 and earlier, parameter: I would s/ parameter:// > +.I flags > +also can contain There's trailing white-space in some lines. Don't worry too much about it; I can remove it while applying. Just wanted to let you know it's there. > +.B O_NONBLOCK > +flag in addition to > +.B O_TRUNC > +flag. > +Behavior depends on the bits set in > +.IR flags . > +In normal usage (see NOTES), the You removed NOTES in this commit. :) > +.B O_NONBLOCK > +flag is always specified, and the > +.B O_TRUNC > +flag may additionally be specified. > +.\" O_TRUNC == KMOD_REMOVE_FORCE in kmod library > +.\" O_NONBLOCK == KMOD_REMOVE_NOWAIT in kmod library > +.IP This should be .P not .IP It was IP where it was before, because it was a continuation of the '(3)' bulletted (_i_ndented) paragraph. > +The various combinations for > +.I flags > +have the following effect: > +.RS And this .RS/.RE pair should also go away. Have a lovely day! Alex > +.TP > +.B flags == O_NONBLOCK > +The call returns immediately, with an error. > +.TP > +.B flags == (O_NONBLOCK | O_TRUNC) > +The module is unloaded immediately, > +regardless of whether it has a nonzero reference count. > +.TP > +.B (flags & O_NONBLOCK) == 0 > +If > +.I flags > +does not specify > +.BR O_NONBLOCK , > +the following steps occur: > +.RS > +.IP \[bu] 3 > +The module is marked so that no new references are permitted. > +.IP \[bu] > +If the module's reference count is nonzero, > +the caller is placed in an uninterruptible sleep state > +.RB ( TASK_UNINTERRUPTIBLE ) > +until the reference count is zero, at which point the call unblocks. > +.IP \[bu] > +The module is unloaded in the usual way. > +.RE > +.RE > .SS Linux 2.4 and earlier > In Linux 2.4 and earlier, the system call took only one argument: > .P > @@ -183,19 +205,9 @@ is NULL, all unused modules marked auto-clean are removed. > .P > Some further details of differences in the behavior of > .BR delete_module () > -in Linux 2.4 and earlier are > +in Linux 3.12 and earlier are > .I not > currently explained in this manual page. > -.SH NOTES > -The uninterruptible sleep that may occur if > -.B O_NONBLOCK > -is omitted from > -.I flags > -is considered undesirable, because the sleeping process is left > -in an unkillable state. > -As at Linux 3.7, specifying > -.B O_NONBLOCK > -is optional, but in future kernels it is likely to become mandatory. > .SH SEE ALSO > .BR create_module (2), > .BR init_module (2), > -- > 2.33.8 > -- <https://www.alejandro-colomar.es/> Looking for a remote C programming job at the moment.
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