git: b3f404d51f29 - stable/12 - Implement GET_STACK_USAGE on remaining archs

The branch stable/12 has been updated by mhorne:

URL: https://cgit.FreeBSD.org/src/commit/?id=b3f404d51f292644fa2b4ade5dc740018a4440e7

commit b3f404d51f292644fa2b4ade5dc740018a4440e7
Author:     Mitchell Horne <mhorne@FreeBSD.org>
AuthorDate: 2021-11-25 16:01:11 +0000
Commit:     Mitchell Horne <mhorne@FreeBSD.org>
CommitDate: 2021-12-07 18:15:59 +0000

    Implement GET_STACK_USAGE on remaining archs
    
    This definition enables callers to estimate remaining space on the
    kstack, and take action on it. Notably, it enables optimizations in the
    GEOM and netgraph subsystems to directly dispatch work items when there
    is sufficient stack space, rather than queuing them for a worker thread.
    
    Implement it for riscv, arm, and mips. Remove the #ifdefs, so it will
    not go unimplemented elsewhere.
    
    PR:             259157
    Reviewed by:    mav, kib, markj (previous version)
    MFC after:      1 week
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D32580
    
    (cherry picked from commit 0d2224733e970aaa67a4e1af7b340044adda92f6)
---
 sys/arm/include/proc.h   | 11 +++++++++++
 sys/geom/geom_io.c       |  8 --------
 sys/mips/include/proc.h  | 11 +++++++++++
 sys/netgraph/ng_base.c   |  3 +--
 sys/riscv/include/proc.h | 11 +++++++++++
 5 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/sys/arm/include/proc.h b/sys/arm/include/proc.h
index d70c7c3df17e..061a3553d1f3 100644
--- a/sys/arm/include/proc.h
+++ b/sys/arm/include/proc.h
@@ -78,4 +78,15 @@ struct syscall_args {
 	u_int nap;
 } __aligned(8);
 
+#ifdef _KERNEL
+#include <machine/pcb.h>
+
+/* Get the current kernel thread stack usage. */
+#define	GET_STACK_USAGE(total, used) do {				\
+	struct thread *td = curthread;					\
+	(total) = td->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb);	\
+	(used) = td->td_kstack + (total) - (vm_offset_t)&td;		\
+} while (0)
+
+#endif  /* _KERNEL */
 #endif /* !_MACHINE_PROC_H_ */
diff --git a/sys/geom/geom_io.c b/sys/geom/geom_io.c
index 65d745bccaf4..c935b35dcc24 100644
--- a/sys/geom/geom_io.c
+++ b/sys/geom/geom_io.c
@@ -584,7 +584,6 @@ g_io_request(struct bio *bp, struct g_consumer *cp)
 	else
 		getbinuptime(&bp->bio_t0);
 
-#ifdef GET_STACK_USAGE
 	direct = (cp->flags & G_CF_DIRECT_SEND) != 0 &&
 	    (pp->flags & G_PF_DIRECT_RECEIVE) != 0 &&
 	    !g_is_geom_thread(curthread) &&
@@ -598,9 +597,6 @@ g_io_request(struct bio *bp, struct g_consumer *cp)
 		if (su * 2 > st)
 			direct = 0;
 	}
-#else
-	direct = 0;
-#endif
 
 	if (!TAILQ_EMPTY(&g_classifier_tailq) && !bp->bio_classifier1) {
 		g_bioq_lock(&g_bio_run_down);
@@ -701,7 +697,6 @@ g_io_deliver(struct bio *bp, int error)
 	bp->bio_bcount = bp->bio_length;
 	bp->bio_resid = bp->bio_bcount - bp->bio_completed;
 
-#ifdef GET_STACK_USAGE
 	direct = (pp->flags & G_PF_DIRECT_SEND) &&
 		 (cp->flags & G_CF_DIRECT_RECEIVE) &&
 		 !g_is_geom_thread(curthread);
@@ -712,9 +707,6 @@ g_io_deliver(struct bio *bp, int error)
 		if (su * 2 > st)
 			direct = 0;
 	}
-#else
-	direct = 0;
-#endif
 
 	/*
 	 * The statistics collection is lockless, as such, but we
diff --git a/sys/mips/include/proc.h b/sys/mips/include/proc.h
index e35e0622513a..99e03a26aa47 100644
--- a/sys/mips/include/proc.h
+++ b/sys/mips/include/proc.h
@@ -98,4 +98,15 @@ struct syscall_args {
 #define	KINFO_PROC_SIZE 816
 #endif
 
+#ifdef _KERNEL
+#include <machine/pcb.h>
+
+/* Get the current kernel thread stack usage. */
+#define	GET_STACK_USAGE(total, used) do {				\
+	struct thread *td = curthread;					\
+	(total) = td->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb);	\
+	(used) = td->td_kstack + (total) - (vm_offset_t)&td;		\
+} while (0)
+
+#endif  /* _KERNEL */
 #endif	/* !_MACHINE_PROC_H_ */
diff --git a/sys/netgraph/ng_base.c b/sys/netgraph/ng_base.c
index 13dd44cd4f4a..1806a442d898 100644
--- a/sys/netgraph/ng_base.c
+++ b/sys/netgraph/ng_base.c
@@ -2281,7 +2281,7 @@ ng_snd_item(item_p item, int flags)
 		queue = 1;
 	} else {
 		queue = 0;
-#ifdef GET_STACK_USAGE
+
 		/*
 		 * Most of netgraph nodes have small stack consumption and
 		 * for them 25% of free stack space is more than enough.
@@ -2296,7 +2296,6 @@ ng_snd_item(item_p item, int flags)
 		    ((node->nd_flags & NGF_HI_STACK) || (hook &&
 		    (hook->hk_flags & HK_HI_STACK)))))
 			queue = 1;
-#endif
 	}
 
 	if (queue) {
diff --git a/sys/riscv/include/proc.h b/sys/riscv/include/proc.h
index 644bb91c4ad6..b8ade8a549d3 100644
--- a/sys/riscv/include/proc.h
+++ b/sys/riscv/include/proc.h
@@ -53,4 +53,15 @@ struct syscall_args {
 	int narg;
 };
 
+#ifdef _KERNEL
+#include <machine/pcb.h>
+
+/* Get the current kernel thread stack usage. */
+#define	GET_STACK_USAGE(total, used) do {				\
+	struct thread *td = curthread;					\
+	(total) = td->td_kstack_pages * PAGE_SIZE - sizeof(struct pcb);	\
+	(used) = td->td_kstack + (total) - (vm_offset_t)&td;		\
+} while (0)
+
+#endif  /* _KERNEL */
 #endif /* !_MACHINE_PROC_H_ */