Re: [PATCH v2 3/6] module: extract patient module check into helper

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On 05.04.23 04:26, Luis Chamberlain wrote:
The patient module check inside add_unformed_module() is large
enough as we need it. It is a bit hard to read too, so just
move it to a helper and do the inverse checks first to help
shift the code and make it easier to read. The new helper then
is module_patient_check_exists().

Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
---
  kernel/module/main.c | 71 +++++++++++++++++++++++++-------------------
  1 file changed, 40 insertions(+), 31 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 98c261928325..8f382580195b 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2638,6 +2638,43 @@ static bool finished_loading(const char *name)
  	return ret;
  }
+/* Must be called with module_mutex held */
+static int module_patient_check_exists(const char *name)
+{
+	struct module *old;
+	int err = 0;
+
+	old = find_module_all(name, strlen(name), true);
+	if (old == NULL)
+		return 0;
+
+	if (old->state == MODULE_STATE_COMING
+	    || old->state == MODULE_STATE_UNFORMED) {

I never understood why people prefer to prefix the || on a newline. But it seems to be a thing in the module/ world :)


+		/* Wait in case it fails to load. */
+		mutex_unlock(&module_mutex);
+		err = wait_event_interruptible(module_wq,
+				       finished_loading(name));
+		if (err)
+			return err;

You return with the mutex unlocked. The caller will unlock again ...

+
+		/* The module might have gone in the meantime. */
+		mutex_lock(&module_mutex);
+		old = find_module_all(name, strlen(name), true);
+	}
+
+	/*
+	 * We are here only when the same module was being loaded. Do
+	 * not try to load it again right now. It prevents long delays
+	 * caused by serialized module load failures. It might happen
+	 * when more devices of the same type trigger load of
+	 * a particular module.
+	 */
+	if (old && old->state == MODULE_STATE_LIVE)
+		return -EEXIST;
+	else
+		return -EBUSY;

You can drop the else and return right away.

+}
+
  /*
   * We try to place it in the list now to make sure it's unique before

Besides, LGTM.

--
Thanks,

David / dhildenb




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