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From 645de09fc84482a55b5234312027efd007e53d8c Mon Sep 17 00:00:00 2001
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From: Adam Jackson <ajax@redhat.com>
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Date: Sat, 7 Nov 2009 15:29:05 -0500
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Subject: [PATCH] xfree86: Use SA_SIGINFO if available for SIGIO handlers
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siginfo_t gives us the file descriptor that raised the signal directly,
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so we don't need to select() for it. This gets evdev event processing
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down to exactly one syscall in the common case.
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Signed-off-by: Adam Jackson <ajax@redhat.com>
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---
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hw/xfree86/os-support/shared/sigio.c | 40 ++++++++++++++++++++++++++++-----
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1 files changed, 34 insertions(+), 6 deletions(-)
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diff --git a/hw/xfree86/os-support/shared/sigio.c b/hw/xfree86/os-support/shared/sigio.c
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index aed5654..4f1ec55 100644
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--- a/hw/xfree86/os-support/shared/sigio.c
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+++ b/hw/xfree86/os-support/shared/sigio.c
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@@ -95,12 +95,11 @@ static int xf86SigIOMax;
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static int xf86SigIOMaxFd;
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static fd_set xf86SigIOMask;
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-/*
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- * SIGIO gives no way of discovering which fd signalled, select
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- * to discover
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- */
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+#ifndef SA_SIGINFO
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+
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+/* plain signals have no way of discovering which fd signalled. */
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static void
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-xf86SIGIO (int sig)
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+sigio_handler (int sig)
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{
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int i;
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fd_set ready;
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@@ -126,6 +125,27 @@ xf86SIGIO (int sig)
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errno = save_errno;
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}
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+#else /* have SA_SIGINFO */
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+
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+/* siginfo passes the triggering fd in, no need to select() */
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+static void
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+sigio_sigaction(int sig, siginfo_t *si, void *ctx)
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+{
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+ int i;
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+ int save_errno = errno;
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+
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+ for (i = 0; i < MAX_FUNCS; i++) {
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+ if (xf86SigIOFuncs[i].f && xf86SigIOFuncs[i].fd == si->si_fd) {
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+ (*xf86SigIOFuncs[i].f)(si->si_fd, xf86SigIOFuncs[i].closure);
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+ break;
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+ }
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+ }
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+
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+ errno = save_errno;
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+}
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+
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+#endif
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+
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static int
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xf86IsPipe (int fd)
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{
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@@ -164,6 +184,9 @@ xf86InstallSIGIOHandler(int fd, void (*f)(int, void *), void *closure)
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xf86Msg(X_WARNING, "fcntl(%d, F_SETOWN): %s\n",
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fd, strerror(errno));
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} else {
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+#ifdef SA_SIGINFO
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+ fcntl(fd, F_SETSIG, SIGIO);
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+#endif
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installed = TRUE;
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}
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}
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@@ -184,8 +207,13 @@ xf86InstallSIGIOHandler(int fd, void (*f)(int, void *), void *closure)
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}
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sigemptyset(&sa.sa_mask);
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sigaddset(&sa.sa_mask, SIGIO);
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+#ifndef SA_SIGINFO
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sa.sa_flags = 0;
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- sa.sa_handler = xf86SIGIO;
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+ sa.sa_handler = sigio_handler;
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+#else
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+ sa.sa_flags = SA_SIGINFO;
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+ sa.sa_sigaction = sigio_sigaction;
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+#endif
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sigaction(SIGIO, &sa, &osa;;
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xf86SigIOFuncs[i].fd = fd;
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xf86SigIOFuncs[i].closure = closure;
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--
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1.6.5.rc2
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