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authorAlexandre Oliva <aoliva@redhat.com>2014-01-31 23:49:07 -0200
committerAlexandre Oliva <aoliva@redhat.com>2014-01-31 23:49:07 -0200
commit542210fbc5cad91c308cb3462245197b616d4338 (patch)
treeb906573ef39a25ca4c5c3e12af856aa3d1196127
parent433c45a2470c5abbd8dd145c7d9fc29553a83525 (diff)
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* manual/setjmp.texi: Document MTASC-safety properties.
-rw-r--r--ChangeLog4
-rw-r--r--manual/setjmp.texi44
2 files changed, 48 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index 75d3c3b4de..5a72530ac4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
2014-01-31 Alexandre Oliva <aoliva@redhat.com>
+ * manual/setjmp.texi: Document MTASC-safety properties.
+
+2014-01-31 Alexandre Oliva <aoliva@redhat.com>
+
* manual/search.texi: Document MTASC-safety properties.
2014-01-31 Alexandre Oliva <aoliva@redhat.com>
diff --git a/manual/setjmp.texi b/manual/setjmp.texi
index b3c0a7ba51..b924d582b1 100644
--- a/manual/setjmp.texi
+++ b/manual/setjmp.texi
@@ -107,6 +107,10 @@ identify a specific place to return to.
@comment setjmp.h
@comment ISO
@deftypefn Macro int setjmp (jmp_buf @var{state})
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+@c _setjmp ok
+@c __sigsetjmp(!savemask) ok
+@c __sigjmp_save(!savemask) ok, does not call sigprocmask
When called normally, @code{setjmp} stores information about the
execution state of the program in @var{state} and returns zero. If
@code{longjmp} is later used to perform a non-local exit to this
@@ -116,6 +120,20 @@ execution state of the program in @var{state} and returns zero. If
@comment setjmp.h
@comment ISO
@deftypefun void longjmp (jmp_buf @var{state}, int @var{value})
+@safety{@prelim{}@mtsafe{}@asunsafe{@ascuplugin{} @asucorrupt{} @asulock{/hurd}}@acunsafe{@acucorrupt{} @aculock{/hurd}}}
+@c __libc_siglongjmp @ascuplugin @asucorrupt @asulock/hurd @acucorrupt @aculock/hurd
+@c _longjmp_unwind @ascuplugin @asucorrupt @acucorrupt
+@c __pthread_cleanup_upto @ascuplugin @asucorrupt @acucorrupt
+@c plugins may be unsafe themselves, but even if they weren't, this
+@c function isn't robust WRT async signals and cancellation:
+@c cleanups aren't taken off the stack right away, only after all
+@c cleanups have been run. This means that async-cancelling
+@c longjmp, or interrupting longjmp with an async signal handler
+@c that calls longjmp may run the same cleanups multiple times.
+@c _JMPBUF_UNWINDS_ADJ ok
+@c *cleanup_buf->__routine @ascuplugin
+@c sigprocmask(SIG_SETMASK) dup @asulock/hurd @aculock/hurd
+@c __longjmp ok
This function restores current execution to the state saved in
@var{state}, and continues execution from the call to @code{setjmp} that
established that return point. Returning from @code{setjmp} by means of
@@ -199,6 +217,11 @@ information about the set of blocked signals.
@comment setjmp.h
@comment POSIX.1
@deftypefun int sigsetjmp (sigjmp_buf @var{state}, int @var{savesigs})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{/hurd}}@acunsafe{@aculock{/hurd}}}
+@c sigsetjmp @asulock/hurd @aculock/hurd
+@c __sigsetjmp(savemask) @asulock/hurd @aculock/hurd
+@c __sigjmp_save(savemask) @asulock/hurd @aculock/hurd
+@c sigprocmask(SIG_BLOCK probe) dup @asulock/hurd @aculock/hurd
This is similar to @code{setjmp}. If @var{savesigs} is nonzero, the set
of blocked signals is saved in @var{state} and will be restored if a
@code{siglongjmp} is later performed with this @var{state}.
@@ -207,6 +230,8 @@ of blocked signals is saved in @var{state} and will be restored if a
@comment setjmp.h
@comment POSIX.1
@deftypefun void siglongjmp (sigjmp_buf @var{state}, int @var{value})
+@safety{@prelim{}@mtsafe{}@asunsafe{@ascuplugin{} @asucorrupt{} @asulock{/hurd}}@acunsafe{@acucorrupt{} @aculock{/hurd}}}
+@c Alias to longjmp.
This is similar to @code{longjmp} except for the type of its @var{state}
argument. If the @code{sigsetjmp} call that set this @var{state} used a
nonzero @var{savesigs} flag, @code{siglongjmp} also restores the set of
@@ -267,6 +292,10 @@ and modification happens through one of the following functions:
@comment ucontext.h
@comment SVID
@deftypefun int getcontext (ucontext_t *@var{ucp})
+@safety{@prelim{}@mtsafe{@mtsrace{:ucp}}@assafe{}@acsafe{}}
+@c Linux-only implementations in assembly, including sigprocmask
+@c syscall. A few cases call the sigprocmask function, but that's safe
+@c too. The ppc case is implemented in terms of a swapcontext syscall.
The @code{getcontext} function initializes the variable pointed to by
@var{ucp} with the context of the calling thread. The context contains
the content of the registers, the signal mask, and the current stack.
@@ -293,6 +322,8 @@ used to do that.
@comment ucontext.h
@comment SVID
@deftypefun void makecontext (ucontext_t *@var{ucp}, void (*@var{func}) (void), int @var{argc}, @dots{})
+@safety{@prelim{}@mtsafe{@mtsrace{:ucp}}@assafe{}@acsafe{}}
+@c Linux-only implementations mostly in assembly, nothing unsafe.
The @var{ucp} parameter passed to the @code{makecontext} shall be
initialized by a call to @code{getcontext}. The context will be
@@ -339,6 +370,15 @@ requires detection of the platform at compile time.
@comment ucontext.h
@comment SVID
@deftypefun int setcontext (const ucontext_t *@var{ucp})
+@safety{@prelim{}@mtsafe{@mtsrace{:ucp}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
+@c Linux-only implementations mostly in assembly. Some ports use
+@c sigreturn or swapcontext syscalls; others restore the signal mask
+@c first and then proceed restore other registers in userland, which
+@c leaves a window for cancellation or async signals with misaligned or
+@c otherwise corrupt stack. ??? Switching to a different stack, or even
+@c to an earlier state on the same stack, may conflict with pthread
+@c cleanups. This is not quite MT-Unsafe, it's a different kind of
+@c safety issue.
The @code{setcontext} function restores the context described by
@var{ucp}. The context is not modified and can be reused as often as
@@ -372,6 +412,10 @@ there are situations where the current context has to be preserved.
@comment ucontext.h
@comment SVID
@deftypefun int swapcontext (ucontext_t *restrict @var{oucp}, const ucontext_t *restrict @var{ucp})
+@safety{@prelim{}@mtsafe{@mtsrace{:oucp} @mtsrace{:ucp}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
+@c Linux-only implementations mostly in assembly. Some ports call or
+@c inline getcontext and/or setcontext, adjusting the saved context in
+@c between, so we inherit the potential issues of both.
The @code{swapcontext} function is similar to @code{setcontext} but
instead of just replacing the current context the latter is first saved