[Xen-changelog] [xen master] console: make printk() line continuation tracking per-CPU

[patchbot@xxxxxxx]

commit 1e8193b5783676087bbd12da6be7641e40073168
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Nov 25 17:18:21 2015 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Nov 25 17:18:21 2015 +0100

    console: make printk() line continuation tracking per-CPU
    
    This avoids cases where split messages (with other than the initial
    part not carrying a log level; single line messages only of course)
    issued on multiple CPUs interfere with each other, causing messages to
    be issued which are supposed to be suppressed due to the log level
    setting. E.g.
    
        CPU A                   CPU B
    XENLOG_G_DEBUG "abc"
                        XENLOG_G_DEBUG "def\n"
    "xyz\n"
    
    would cause the last message to be logged despite this obviously not
    being intended (at default log levels).
    
    Suggested-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Tested-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/drivers/char/console.c |   27 +++++++++++++++------------
 1 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 4362400..e0083f1 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -620,15 +620,18 @@ static void printk_start_of_line(const char *prefix)
 
 static void vprintk_common(const char *prefix, const char *fmt, va_list args)
 {
+    struct vps {
+        bool_t continued, do_print;
+    }            *state;
+    static DEFINE_PER_CPU(struct vps, state);
     static char   buf[1024];
-    static int    start_of_line = 1, do_print;
-
     char         *p, *q;
     unsigned long flags;
 
     /* console_lock can be acquired recursively from __printk_ratelimit(). */
     local_irq_save(flags);
     spin_lock_recursive(&console_lock);
+    state = &this_cpu(state);
 
     (void)vsnprintf(buf, sizeof(buf), fmt, args);
 
@@ -637,30 +640,30 @@ static void vprintk_common(const char *prefix, const char 
*fmt, va_list args)
     while ( (q = strchr(p, '\n')) != NULL )
     {
         *q = '\0';
-        if ( start_of_line )
-            do_print = printk_prefix_check(p, &p);
-        if ( do_print )
+        if ( !state->continued )
+            state->do_print = printk_prefix_check(p, &p);
+        if ( state->do_print )
         {
-            if ( start_of_line )
+            if ( !state->continued )
                 printk_start_of_line(prefix);
             __putstr(p);
             __putstr("\n");
         }
-        start_of_line = 1;
+        state->continued = 0;
         p = q + 1;
     }
 
     if ( *p != '\0' )
     {
-        if ( start_of_line )
-            do_print = printk_prefix_check(p, &p);
-        if ( do_print )
+        if ( !state->continued )
+            state->do_print = printk_prefix_check(p, &p);
+        if ( state->do_print )
         {
-            if ( start_of_line )
+            if ( !state->continued )
                 printk_start_of_line(prefix);
             __putstr(p);
         }
-        start_of_line = 0;
+        state->continued = 1;
     }
 
     spin_unlock_recursive(&console_lock);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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