printk: allocate kernel log buffer earlier

On larger systems, because of the numerous ACPI, Bootmem and EFI messages,
the static log buffer overflows before the larger one specified by the
log_buf_len param is allocated.  Minimize the overflow by allocating the
new log buffer as soon as possible.

On kernels without memblock, a later call to setup_log_buf from
kernel/init.c is the fallback.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_PRINTK=n build]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 605e5ae..a3e5948 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -946,6 +946,8 @@ void __init setup_arch(char **cmdline_p)
        if (init_ohci1394_dma_early)
                init_ohci1394_dma_on_all_controllers();
 #endif
+       /* Allocate bigger log buffer */
+       setup_log_buf(1);
 
        reserve_initrd();
 

diff --git a/include/linux/printk.h b/include/linux/printk.h
index ee048e7..0101d55 100644 (file)
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -1,6 +1,8 @@
 #ifndef __KERNEL_PRINTK__
 #define __KERNEL_PRINTK__
 
+#include <linux/init.h>
+
 extern const char linux_banner[];
 extern const char linux_proc_banner[];
 
@@ -113,6 +115,7 @@ extern int dmesg_restrict;
 extern int kptr_restrict;
 
 void log_buf_kexec_setup(void);
+void __init setup_log_buf(int early);
 #else
 static inline __attribute__ ((format (printf, 1, 0)))
 int vprintk(const char *s, va_list args)
@@ -137,6 +140,10 @@ static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 static inline void log_buf_kexec_setup(void)
 {
 }
+
+static inline void setup_log_buf(int early)
+{
+}
 #endif
 
 extern void dump_stack(void) __cold;

diff --git a/init/main.c b/init/main.c
index 22da339..d2f1e08 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -504,6 +504,7 @@ asmlinkage void __init start_kernel(void)
         * These use large bootmem allocations and must precede
         * kmem_cache_init()
         */
+       setup_log_buf(0);
        pidhash_init();
        vfs_caches_init_early();
        sort_main_extable();

diff --git a/kernel/printk.c b/kernel/printk.c
index da8ca81..3518539 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -31,6 +31,7 @@
 #include <linux/smp.h>
 #include <linux/security.h>
 #include <linux/bootmem.h>
+#include <linux/memblock.h>
 #include <linux/syscalls.h>
 #include <linux/kexec.h>
 #include <linux/kdb.h>
@@ -167,46 +168,74 @@ void log_buf_kexec_setup(void)
 }
 #endif
 
+/* requested log_buf_len from kernel cmdline */
+static unsigned long __initdata new_log_buf_len;
+
+/* save requested log_buf_len since it's too early to process it */
 static int __init log_buf_len_setup(char *str)
 {
        unsigned size = memparse(str, &str);
-       unsigned long flags;
 
        if (size)
                size = roundup_pow_of_two(size);
-       if (size > log_buf_len) {
-               unsigned start, dest_idx, offset;
-               char *new_log_buf;
+       if (size > log_buf_len)
+               new_log_buf_len = size;
 
-               new_log_buf = alloc_bootmem(size);
-               if (!new_log_buf) {
-                       printk(KERN_WARNING "log_buf_len: allocation failed\n");
-                       goto out;
-               }
+       return 0;
+}
+early_param("log_buf_len", log_buf_len_setup);
 
-               spin_lock_irqsave(&logbuf_lock, flags);
-               log_buf_len = size;
-               log_buf = new_log_buf;
-
-               offset = start = min(con_start, log_start);
-               dest_idx = 0;
-               while (start != log_end) {
-                       log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];
-                       start++;
-                       dest_idx++;
-               }
-               log_start -= offset;
-               con_start -= offset;
-               log_end -= offset;
-               spin_unlock_irqrestore(&logbuf_lock, flags);
+void __init setup_log_buf(int early)
+{
+       unsigned long flags;
+       unsigned start, dest_idx, offset;
+       char *new_log_buf;
+       int free;
+
+       if (!new_log_buf_len)
+               return;
+
+       if (early) {
+               unsigned long mem;
 
-               printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
+               mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
+               if (mem == MEMBLOCK_ERROR)
+                       return;
+               new_log_buf = __va(mem);
+       } else {
+               new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
        }
-out:
-       return 1;
-}
 
-__setup("log_buf_len=", log_buf_len_setup);
+       if (unlikely(!new_log_buf)) {
+               pr_err("log_buf_len: %ld bytes not available\n",
+                       new_log_buf_len);
+               return;
+       }
+
+       spin_lock_irqsave(&logbuf_lock, flags);
+       log_buf_len = new_log_buf_len;
+       log_buf = new_log_buf;
+       new_log_buf_len = 0;
+       free = __LOG_BUF_LEN - log_end;
+
+       offset = start = min(con_start, log_start);
+       dest_idx = 0;
+       while (start != log_end) {
+               unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1);
+
+               log_buf[dest_idx] = __log_buf[log_idx_mask];
+               start++;
+               dest_idx++;
+       }
+       log_start -= offset;
+       con_start -= offset;
+       log_end -= offset;
+       spin_unlock_irqrestore(&logbuf_lock, flags);
+
+       pr_info("log_buf_len: %d\n", log_buf_len);
+       pr_info("early log buf free: %d(%d%%)\n",
+               free, (free * 100) / __LOG_BUF_LEN);
+}
 
 #ifdef CONFIG_BOOT_PRINTK_DELAY