Author: sephe
Date: Fri Oct 14 02:03:53 2016
New Revision: 307244
URL: https://svnweb.freebsd.org/changeset/base/307244

Log:
  MFC 305722
  
      x86: Use sx lock for interrupt sources.
  
      - Certain pic_assign_cpu, e.g. msi_assign_cpu can have quite a long
        call chain.  For msi_assign_cpu, mutex makes complex PCI bridge
        drivers more tricky, e.g. sleep can note be called, etc, it will
        be pretty tricky for upcoming Hyper-V PCI bridge driver for PCI
        pass-through.
      - It is not used on any hot code path nor non-sleepable context, so
        sx should have the same effect as mutex.
  
      PIC list is still protected by mutex to keep suspend/resume work.
  
      Discussed with: jhb
      Reviewed by:    jhb
      Sponsored by:   Microsoft
      Differential Revision:  https://reviews.freebsd.org/D7784

Modified:
  stable/10/sys/x86/x86/intr_machdep.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/x86/x86/intr_machdep.c
==============================================================================
--- stable/10/sys/x86/x86/intr_machdep.c        Fri Oct 14 01:53:15 2016        
(r307243)
+++ stable/10/sys/x86/x86/intr_machdep.c        Fri Oct 14 02:03:53 2016        
(r307244)
@@ -46,6 +46,7 @@
 #include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/smp.h>
+#include <sys/sx.h>
 #include <sys/syslog.h>
 #include <sys/systm.h>
 #include <machine/clock.h>
@@ -73,7 +74,8 @@ typedef void (*mask_fn)(void *);
 
 static int intrcnt_index;
 static struct intsrc *interrupt_sources[NUM_IO_INTS];
-static struct mtx intr_table_lock;
+static struct sx intrsrc_lock;
+static struct mtx intrpic_lock;
 static struct mtx intrcnt_lock;
 static TAILQ_HEAD(pics_head, pic) pics;
 
@@ -117,14 +119,14 @@ intr_register_pic(struct pic *pic)
 {
        int error;
 
-       mtx_lock(&intr_table_lock);
+       mtx_lock(&intrpic_lock);
        if (intr_pic_registered(pic))
                error = EBUSY;
        else {
                TAILQ_INSERT_TAIL(&pics, pic, pics);
                error = 0;
        }
-       mtx_unlock(&intr_table_lock);
+       mtx_unlock(&intrpic_lock);
        return (error);
 }
 
@@ -148,16 +150,16 @@ intr_register_source(struct intsrc *isrc
            vector);
        if (error)
                return (error);
-       mtx_lock(&intr_table_lock);
+       sx_xlock(&intrsrc_lock);
        if (interrupt_sources[vector] != NULL) {
-               mtx_unlock(&intr_table_lock);
+               sx_xunlock(&intrsrc_lock);
                intr_event_destroy(isrc->is_event);
                return (EEXIST);
        }
        intrcnt_register(isrc);
        interrupt_sources[vector] = isrc;
        isrc->is_handlers = 0;
-       mtx_unlock(&intr_table_lock);
+       sx_xunlock(&intrsrc_lock);
        return (0);
 }
 
@@ -181,14 +183,14 @@ intr_add_handler(const char *name, int v
        error = intr_event_add_handler(isrc->is_event, name, filter, handler,
            arg, intr_priority(flags), flags, cookiep);
        if (error == 0) {
-               mtx_lock(&intr_table_lock);
+               sx_xlock(&intrsrc_lock);
                intrcnt_updatename(isrc);
                isrc->is_handlers++;
                if (isrc->is_handlers == 1) {
                        isrc->is_pic->pic_enable_intr(isrc);
                        isrc->is_pic->pic_enable_source(isrc);
                }
-               mtx_unlock(&intr_table_lock);
+               sx_xunlock(&intrsrc_lock);
        }
        return (error);
 }
@@ -202,14 +204,14 @@ intr_remove_handler(void *cookie)
        isrc = intr_handler_source(cookie);
        error = intr_event_remove_handler(cookie);
        if (error == 0) {
-               mtx_lock(&intr_table_lock);
+               sx_xlock(&intrsrc_lock);
                isrc->is_handlers--;
                if (isrc->is_handlers == 0) {
                        isrc->is_pic->pic_disable_source(isrc, PIC_NO_EOI);
                        isrc->is_pic->pic_disable_intr(isrc);
                }
                intrcnt_updatename(isrc);
-               mtx_unlock(&intr_table_lock);
+               sx_xunlock(&intrsrc_lock);
        }
        return (error);
 }
@@ -283,12 +285,12 @@ intr_resume(bool suspend_cancelled)
 #ifndef DEV_ATPIC
        atpic_reset();
 #endif
-       mtx_lock(&intr_table_lock);
+       mtx_lock(&intrpic_lock);
        TAILQ_FOREACH(pic, &pics, pics) {
                if (pic->pic_resume != NULL)
                        pic->pic_resume(pic, suspend_cancelled);
        }
-       mtx_unlock(&intr_table_lock);
+       mtx_unlock(&intrpic_lock);
 }
 
 void
@@ -296,12 +298,12 @@ intr_suspend(void)
 {
        struct pic *pic;
 
-       mtx_lock(&intr_table_lock);
+       mtx_lock(&intrpic_lock);
        TAILQ_FOREACH_REVERSE(pic, &pics, pics_head, pics) {
                if (pic->pic_suspend != NULL)
                        pic->pic_suspend(pic);
        }
-       mtx_unlock(&intr_table_lock);
+       mtx_unlock(&intrpic_lock);
 }
 
 static int
@@ -317,9 +319,9 @@ intr_assign_cpu(void *arg, u_char cpu)
         */
        if (assign_cpu && cpu != NOCPU) {
                isrc = arg;
-               mtx_lock(&intr_table_lock);
+               sx_xlock(&intrsrc_lock);
                error = isrc->is_pic->pic_assign_cpu(isrc, cpu_apic_ids[cpu]);
-               mtx_unlock(&intr_table_lock);
+               sx_xunlock(&intrsrc_lock);
        } else
                error = 0;
        return (error);
@@ -379,7 +381,8 @@ intr_init(void *dummy __unused)
        intrcnt_setname("???", 0);
        intrcnt_index = 1;
        TAILQ_INIT(&pics);
-       mtx_init(&intr_table_lock, "intr sources", NULL, MTX_DEF);
+       mtx_init(&intrpic_lock, "intrpic", NULL, MTX_DEF);
+       sx_init(&intrsrc_lock, "intrsrc");
        mtx_init(&intrcnt_lock, "intrcnt", NULL, MTX_SPIN);
 }
 SYSINIT(intr_init, SI_SUB_INTR, SI_ORDER_FIRST, intr_init, NULL);
@@ -527,7 +530,7 @@ intr_shuffle_irqs(void *arg __unused)
                return;
 
        /* Round-robin assign a CPU to each enabled source. */
-       mtx_lock(&intr_table_lock);
+       sx_xlock(&intrsrc_lock);
        assign_cpu = 1;
        for (i = 0; i < NUM_IO_INTS; i++) {
                isrc = interrupt_sources[i];
@@ -548,7 +551,7 @@ intr_shuffle_irqs(void *arg __unused)
 
                }
        }
-       mtx_unlock(&intr_table_lock);
+       sx_xunlock(&intrsrc_lock);
 }
 SYSINIT(intr_shuffle_irqs, SI_SUB_SMP, SI_ORDER_SECOND, intr_shuffle_irqs,
     NULL);
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