[IA64] SAL to OS callbacks cannot call sleeping

When SAL calls back into the OS, the OS code is running with preempt
disabled so it cannot call sleeping functions.

Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 21 insertions, 13 deletions

diff --git a/arch/ia64/sn/kernel/mca.c b/arch/ia64/sn/kernel/mca.c
index 857774bb2c9a..6546db6abdba 100644
--- a/arch/ia64/sn/kernel/mca.c
+++ b/arch/ia64/sn/kernel/mca.c
@@ -37,6 +37,11 @@ static u64 *sn_oemdata_size, sn_oemdata_bufsize;
  * This function is the callback routine that SAL calls to log error
  * info for platform errors.  buf is appended to sn_oemdata, resizing as
  * required.
+ * Note: this is a SAL to OS callback, running under the same rules as the SAL
+ * code.  SAL calls are run with preempt disabled so this routine must not
+ * sleep.  vmalloc can sleep so print_hook cannot resize the output buffer
+ * itself, instead it must set the required size and return to let the caller
+ * resize the buffer then redrive the SAL call.
  */
 static int print_hook(const char *fmt, ...)
 {
@@ -47,18 +52,8 @@ static int print_hook(const char *fmt, ...)
         vsnprintf(buf, sizeof(buf), fmt, args);
         va_end(args);
         len = strlen(buf);
-        while (*sn_oemdata_size + len + 1 > sn_oemdata_bufsize) {
-                u8 *newbuf = vmalloc(sn_oemdata_bufsize += 1000);
-                if (!newbuf) {
-                        printk(KERN_ERR "%s: unable to extend sn_oemdata\n",
-                               __FUNCTION__);
-                        return 0;
-                }
-                memcpy(newbuf, *sn_oemdata, *sn_oemdata_size);
-                vfree(*sn_oemdata);
-                *sn_oemdata = newbuf;
-        }
-        memcpy(*sn_oemdata + *sn_oemdata_size, buf, len + 1);
+        if (*sn_oemdata_size + len <= sn_oemdata_bufsize)
+                memcpy(*sn_oemdata + *sn_oemdata_size, buf, len);
         *sn_oemdata_size += len;
         return 0;
 }
@@ -98,7 +93,20 @@ sn_platform_plat_specific_err_print(const u8 * sect_header, u8 ** oemdata,
         sn_oemdata = oemdata;
         sn_oemdata_size = oemdata_size;
         sn_oemdata_bufsize = 0;
-        ia64_sn_plat_specific_err_print(print_hook, (char *)sect_header);
+        *sn_oemdata_size = PAGE_SIZE;   /* first guess at how much data will be generated */
+        while (*sn_oemdata_size > sn_oemdata_bufsize) {
+                u8 *newbuf = vmalloc(*sn_oemdata_size);
+                if (!newbuf) {
+                        printk(KERN_ERR "%s: unable to extend sn_oemdata\n",
+                               __FUNCTION__);
+                        return 1;
+                }
+                vfree(*sn_oemdata);
+                *sn_oemdata = newbuf;
+                sn_oemdata_bufsize = *sn_oemdata_size;
+                *sn_oemdata_size = 0;
+                ia64_sn_plat_specific_err_print(print_hook, (char *)sect_header);
+        }
         up(&sn_oemdata_mutex);
         return 0;
 }