svn commit: r324785 - in head/sys/amd64: amd64 ia32 linux linux32

[Mateusz Guzik]

Author: mjg
Date: Fri Oct 20 03:30:02 2017
New Revision: 324785
URL: https://svnweb.freebsd.org/changeset/base/324785

Log:
  amd64: avoid acquiring dt lock if possible (which is the common case)
  
  Discussed with:	kib
  MFC after:	1 week

Modified:
  head/sys/amd64/amd64/machdep.c
  head/sys/amd64/amd64/sys_machdep.c
  head/sys/amd64/amd64/vm_machdep.c
  head/sys/amd64/ia32/ia32_signal.c
  head/sys/amd64/linux/linux_sysvec.c
  head/sys/amd64/linux32/linux32_sysvec.c

Modified: head/sys/amd64/amd64/machdep.c
==============================================================================
--- head/sys/amd64/amd64/machdep.c	Fri Oct 20 03:13:31 2017	(r324784)
+++ head/sys/amd64/amd64/machdep.c	Fri Oct 20 03:30:02 2017	(r324785)
@@ -581,12 +581,9 @@ exec_setregs(struct thread *td, struct image_params *i
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
 
-	mtx_lock(&dt_lock);
 	if (td->td_proc->p_md.md_ldt != NULL)
 		user_ldt_free(td);
-	else
-		mtx_unlock(&dt_lock);
-	
+
 	update_pcb_bases(pcb);
 	pcb->pcb_fsbase = 0;
 	pcb->pcb_gsbase = 0;

Modified: head/sys/amd64/amd64/sys_machdep.c
==============================================================================
--- head/sys/amd64/amd64/sys_machdep.c	Fri Oct 20 03:13:31 2017	(r324784)
+++ head/sys/amd64/amd64/sys_machdep.c	Fri Oct 20 03:30:02 2017	(r324785)
@@ -500,7 +500,7 @@ user_ldt_free(struct thread *td)
 	struct mdproc *mdp = &p->p_md;
 	struct proc_ldt *pldt;
 
-	mtx_assert(&dt_lock, MA_OWNED);
+	mtx_lock(&dt_lock);
 	if ((pldt = mdp->md_ldt) == NULL) {
 		mtx_unlock(&dt_lock);
 		return;

Modified: head/sys/amd64/amd64/vm_machdep.c
==============================================================================
--- head/sys/amd64/amd64/vm_machdep.c	Fri Oct 20 03:13:31 2017	(r324784)
+++ head/sys/amd64/amd64/vm_machdep.c	Fri Oct 20 03:30:02 2017	(r324785)
@@ -299,11 +299,8 @@ cpu_exit(struct thread *td)
 	/*
 	 * If this process has a custom LDT, release it.
 	 */
-	mtx_lock(&dt_lock);
-	if (td->td_proc->p_md.md_ldt != 0)
+	if (td->td_proc->p_md.md_ldt != NULL)
 		user_ldt_free(td);
-	else
-		mtx_unlock(&dt_lock);
 }
 
 void

Modified: head/sys/amd64/ia32/ia32_signal.c
==============================================================================
--- head/sys/amd64/ia32/ia32_signal.c	Fri Oct 20 03:13:31 2017	(r324784)
+++ head/sys/amd64/ia32/ia32_signal.c	Fri Oct 20 03:30:02 2017	(r324785)
@@ -937,12 +937,9 @@ ia32_setregs(struct thread *td, struct image_params *i
 {
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
-	
-	mtx_lock(&dt_lock);
+
 	if (td->td_proc->p_md.md_ldt != NULL)
 		user_ldt_free(td);
-	else
-		mtx_unlock(&dt_lock);
 #ifdef COMPAT_43
 	setup_lcall_gate();
 #endif

Modified: head/sys/amd64/linux/linux_sysvec.c
==============================================================================
--- head/sys/amd64/linux/linux_sysvec.c	Fri Oct 20 03:13:31 2017	(r324784)
+++ head/sys/amd64/linux/linux_sysvec.c	Fri Oct 20 03:30:02 2017	(r324785)
@@ -453,11 +453,8 @@ linux_exec_setregs(struct thread *td, struct image_par
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
 
-	mtx_lock(&dt_lock);
 	if (td->td_proc->p_md.md_ldt != NULL)
 		user_ldt_free(td);
-	else
-		mtx_unlock(&dt_lock);
 
 	pcb->pcb_fsbase = 0;
 	pcb->pcb_gsbase = 0;

Modified: head/sys/amd64/linux32/linux32_sysvec.c
==============================================================================
--- head/sys/amd64/linux32/linux32_sysvec.c	Fri Oct 20 03:13:31 2017	(r324784)
+++ head/sys/amd64/linux32/linux32_sysvec.c	Fri Oct 20 03:30:02 2017	(r324785)
@@ -804,11 +804,8 @@ exec_linux_setregs(struct thread *td, struct image_par
 	struct trapframe *regs = td->td_frame;
 	struct pcb *pcb = td->td_pcb;
 
-	mtx_lock(&dt_lock);
 	if (td->td_proc->p_md.md_ldt != NULL)
 		user_ldt_free(td);
-	else
-		mtx_unlock(&dt_lock);
 
 	critical_enter();
 	wrmsr(MSR_FSBASE, 0);