Re: [PATCH 1/7] signal.h: Define SIGINFO on all architectures
From: Eric W. Biederman <hidden>
Date: 2019-06-11 20:42:23
Also in:
lkml
Arseny Maslennikov [off-list ref] writes:
This complementary patch defines SIGINFO as a synonym for SIGPWR on every architecture supported by the kernel. The particular signal number chosen does not really matter and is only required for the related tty functionality to work properly, so if it does not suite expectations, any suggestions are warmly welcome. SIGPWR looks like a nice candidate for this role, because it is defined on every supported arch; it is currently only used to inform PID 1 of power failures, and daemons that care about low-level events do not tend to have a controlling terminal. However, on sparcs SIGPWR is a synonym for SIGLOST, a signal unique to that architecture, with a narrow set of intended uses that do not combine well with interactively requesting status. SIGLOST is not used by any kernel code at the moment. I'm not sure there is a more reasonable alternative right now.
Is the name SIGINFO already well established. It just is a little bit confusing with struct siginfo. At least on x86 it looks like we have signals 32 and 33 that are reserved and not used for anything. Is there a reason you have not picked one of those? Also should this be a realtime signal with signal information or a non-realtime signal? I don't expect there is much to encode except that the user is asking for information. I half wonder if it could be done as a different si_code to SIGWINCH. But of course that doesn't work because it is not a real time signal so does not queue more than one siginfo. (Sigh). I just would like to see that we have a clear concept of how this new signal plays into all of the signal handling bits. Added linux-api because this is fundamentally extending the linux-api, and we probably want man-page updates etc. Eric
quoted hunk
Signed-off-by: Arseny Maslennikov <redacted> --- arch/arm/include/uapi/asm/signal.h | 1 + arch/h8300/include/uapi/asm/signal.h | 1 + arch/ia64/include/uapi/asm/signal.h | 1 + arch/m68k/include/uapi/asm/signal.h | 1 + arch/mips/include/uapi/asm/signal.h | 1 + arch/parisc/include/uapi/asm/signal.h | 1 + arch/powerpc/include/uapi/asm/signal.h | 1 + arch/s390/include/uapi/asm/signal.h | 1 + arch/sparc/include/uapi/asm/signal.h | 2 ++ arch/x86/include/uapi/asm/signal.h | 1 + arch/xtensa/include/uapi/asm/signal.h | 1 + include/uapi/asm-generic/signal.h | 1 + 12 files changed, 13 insertions(+)diff --git a/arch/arm/include/uapi/asm/signal.h b/arch/arm/include/uapi/asm/signal.h index 9b4185ba4f8a..b80b53a17267 100644 --- a/arch/arm/include/uapi/asm/signal.h +++ b/arch/arm/include/uapi/asm/signal.h@@ -50,6 +50,7 @@ typedef unsigned long sigset_t; #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31diff --git a/arch/h8300/include/uapi/asm/signal.h b/arch/h8300/include/uapi/asm/signal.h index e15521037348..7a2b783af22b 100644 --- a/arch/h8300/include/uapi/asm/signal.h +++ b/arch/h8300/include/uapi/asm/signal.h@@ -50,6 +50,7 @@ typedef unsigned long sigset_t; #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31diff --git a/arch/ia64/include/uapi/asm/signal.h b/arch/ia64/include/uapi/asm/signal.h index aa98ff1b9e22..b4c98cb17165 100644 --- a/arch/ia64/include/uapi/asm/signal.h +++ b/arch/ia64/include/uapi/asm/signal.h@@ -45,6 +45,7 @@ #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 /* signal 31 is no longer "unused", but the SIGUNUSED macro remains for backwards compatibility */ #define SIGUNUSED 31diff --git a/arch/m68k/include/uapi/asm/signal.h b/arch/m68k/include/uapi/asm/signal.h index 915cc755a184..a0b4e4108cb8 100644 --- a/arch/m68k/include/uapi/asm/signal.h +++ b/arch/m68k/include/uapi/asm/signal.h@@ -50,6 +50,7 @@ typedef unsigned long sigset_t; #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31diff --git a/arch/mips/include/uapi/asm/signal.h b/arch/mips/include/uapi/asm/signal.h index 53104b10aae2..975a6f0d3b0b 100644 --- a/arch/mips/include/uapi/asm/signal.h +++ b/arch/mips/include/uapi/asm/signal.h@@ -43,6 +43,7 @@ typedef unsigned long old_sigset_t; /* at least 32 bits */ #define SIGCHLD 18 /* Child status has changed (POSIX). */ #define SIGCLD SIGCHLD /* Same as SIGCHLD (System V). */ #define SIGPWR 19 /* Power failure restart (System V). */ +#define SIGINFO SIGPWR /* Keyboard status request (4.2 BSD). */ #define SIGWINCH 20 /* Window size change (4.3 BSD, Sun). */ #define SIGURG 21 /* Urgent condition on socket (4.2 BSD). */ #define SIGIO 22 /* I/O now possible (4.2 BSD). */diff --git a/arch/parisc/include/uapi/asm/signal.h b/arch/parisc/include/uapi/asm/signal.h index d38563a394f2..fe2e00d590ac 100644 --- a/arch/parisc/include/uapi/asm/signal.h +++ b/arch/parisc/include/uapi/asm/signal.h@@ -22,6 +22,7 @@ #define SIGUSR2 17 #define SIGCHLD 18 #define SIGPWR 19 +#define SIGINFO SIGPWR #define SIGVTALRM 20 #define SIGPROF 21 #define SIGIO 22diff --git a/arch/powerpc/include/uapi/asm/signal.h b/arch/powerpc/include/uapi/asm/signal.h index 85b0a7aa43e7..e7f3885905b4 100644 --- a/arch/powerpc/include/uapi/asm/signal.h +++ b/arch/powerpc/include/uapi/asm/signal.h@@ -53,6 +53,7 @@ typedef struct { #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31diff --git a/arch/s390/include/uapi/asm/signal.h b/arch/s390/include/uapi/asm/signal.h index 9a14a611ed82..12ee62987971 100644 --- a/arch/s390/include/uapi/asm/signal.h +++ b/arch/s390/include/uapi/asm/signal.h@@ -58,6 +58,7 @@ typedef unsigned long sigset_t; #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31diff --git a/arch/sparc/include/uapi/asm/signal.h b/arch/sparc/include/uapi/asm/signal.h index ff9505923b9a..b655163198bb 100644 --- a/arch/sparc/include/uapi/asm/signal.h +++ b/arch/sparc/include/uapi/asm/signal.h@@ -71,6 +71,8 @@ #define SIGWINCH 28 #define SIGLOST 29 #define SIGPWR SIGLOST +/* XXX: is it OK for SIGINFO to collide with LOST? */ +#define SIGINFO SIGPWR #define SIGUSR1 30 #define SIGUSR2 31diff --git a/arch/x86/include/uapi/asm/signal.h b/arch/x86/include/uapi/asm/signal.h index e5745d593dc7..1539bb28826c 100644 --- a/arch/x86/include/uapi/asm/signal.h +++ b/arch/x86/include/uapi/asm/signal.h@@ -55,6 +55,7 @@ typedef unsigned long sigset_t; #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31diff --git a/arch/xtensa/include/uapi/asm/signal.h b/arch/xtensa/include/uapi/asm/signal.h index 005dec5bfde4..d644234305de 100644 --- a/arch/xtensa/include/uapi/asm/signal.h +++ b/arch/xtensa/include/uapi/asm/signal.h@@ -65,6 +65,7 @@ typedef struct { #define SIGPOLL SIGIO /* #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31diff --git a/include/uapi/asm-generic/signal.h b/include/uapi/asm-generic/signal.h index 5c716a952cbe..9f9a1db0d43c 100644 --- a/include/uapi/asm-generic/signal.h +++ b/include/uapi/asm-generic/signal.h@@ -43,6 +43,7 @@ #define SIGLOST 29 */ #define SIGPWR 30 +#define SIGINFO SIGPWR #define SIGSYS 31 #define SIGUNUSED 31