kmod: throttle kmod thread limit

[sfrench/cifs-2.6.git] / kernel / kmod.c

diff --git a/kernel/kmod.c b/kernel/kmod.c
index ff68198fe83bcb6b9edfcc9999ff57288e322de7..6d016c5d97c8390f561e6a9456a4e0c1ca59bffe 100644 (file)
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -68,6 +68,7 @@ static DECLARE_RWSEM(umhelper_sem);
  */
 #define MAX_KMOD_CONCURRENT 50
 static atomic_t kmod_concurrent_max = ATOMIC_INIT(MAX_KMOD_CONCURRENT);
+static DECLARE_WAIT_QUEUE_HEAD(kmod_wq);
 
 /*
        modprobe_path is set via /proc/sys.
@@ -140,7 +141,6 @@ int __request_module(bool wait, const char *fmt, ...)
        va_list args;
        char module_name[MODULE_NAME_LEN];
        int ret;
-       static int kmod_loop_msg;
 
        /*
         * We don't allow synchronous module loading from async.  Module
@@ -164,14 +164,11 @@ int __request_module(bool wait, const char *fmt, ...)
                return ret;
 
        if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) {
-               /* We may be blaming an innocent here, but unlikely */
-               if (kmod_loop_msg < 5) {
-                       printk(KERN_ERR
-                              "request_module: runaway loop modprobe %s\n",
-                              module_name);
-                       kmod_loop_msg++;
-               }
-               return -ENOMEM;
+               pr_warn_ratelimited("request_module: kmod_concurrent_max (%u) close to 0 (max_modprobes: %u), for module %s, throttling...",
+                                   atomic_read(&kmod_concurrent_max),
+                                   MAX_KMOD_CONCURRENT, module_name);
+               wait_event_interruptible(kmod_wq,
+                                        atomic_dec_if_positive(&kmod_concurrent_max) >= 0);
        }
 
        trace_module_request(module_name, wait, _RET_IP_);
@@ -179,6 +176,7 @@ int __request_module(bool wait, const char *fmt, ...)
        ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
 
        atomic_inc(&kmod_concurrent_max);
+       wake_up(&kmod_wq);
 
        return ret;
 }