[PATCH 1/1] MdeModulePkg/UefiBootManagerLib: limit recursive call depth

[Heyi Guo <heyi.guo@linaro.org>]

Function BmRepairAllControllers may recursively call itself if some
driver health protocol returns EfiDriverHealthStatusReconnectRequired.
However, driver health protocol of some buggy third party driver may
always return such status even after one and another reconnect. The
endless iteration will cause stack overflow and then system exception,
and it may be not easy to find that the exception is actually caused
by stack overflow.

So we limit the number of reconnect retry to 10 to improve code
robustness, and DEBUG_CODE is moved ahead before recursive repair to
track the repair result.

We also remove a duplicated declaration of BmRepairAllControllers() in
InternalBm.h in this patch, for it is only a trivial change.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Heyi Guo <heyi.guo@linaro.org>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
---

Notes:
    v2
    - Use argument instead of global variable to record the recursive
      count [Ray]
    - Move DEBUG_CODE before recursively calling BmRepairAllControllers()
      to track the change of each reconnect [Ray]
    - Remove a duplicated declaration of BmRepairAllControllers() in
      InternalBm.h.

 MdeModulePkg/Library/UefiBootManagerLib/InternalBm.h     | 19 ++++++++++---------
 MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c         |  2 +-
 MdeModulePkg/Library/UefiBootManagerLib/BmDriverHealth.c | 18 +++++++++++++-----
 3 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/MdeModulePkg/Library/UefiBootManagerLib/InternalBm.h b/MdeModulePkg/Library/UefiBootManagerLib/InternalBm.h
index 25a1d522fe84..21ecd8584d24 100644
--- a/MdeModulePkg/Library/UefiBootManagerLib/InternalBm.h
+++ b/MdeModulePkg/Library/UefiBootManagerLib/InternalBm.h
@@ -108,6 +108,12 @@ CHAR16 *
 #define BM_OPTION_NAME_LEN                          sizeof ("PlatformRecovery####")
 extern CHAR16  *mBmLoadOptionName[];
 
+//
+// Maximum number of reconnect retry to repair controller; it is to limit the
+// number of recursive call of BmRepairAllControllers.
+//
+#define MAX_RECONNECT_REPAIR                        10
+
 /**
   Visitor function to be called by BmForEachVariable for each variable
   in variable storage.
@@ -145,10 +151,13 @@ typedef struct {
 
 /**
   Repair all the controllers according to the Driver Health status queried.
+
+  @param ReconnectRepairCount     To record the number of recursive call of
+                                  this function itself.
 **/
 VOID
 BmRepairAllControllers (
-  VOID
+  UINTN       ReconnectRepairCount
   );
 
 #define BM_HOTKEY_SIGNATURE SIGNATURE_32 ('b', 'm', 'h', 'k')
@@ -328,14 +337,6 @@ BmDelPartMatchInstance (
   );
 
 /**
-  Repair all the controllers according to the Driver Health status queried.
-**/
-VOID
-BmRepairAllControllers (
-  VOID
-  );
-
-/**
   Print the device path info.
 
   @param DevicePath           The device path need to print.
diff --git a/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c b/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
index ce19ae400660..b842d5824aed 100644
--- a/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
+++ b/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
@@ -1767,7 +1767,7 @@ EfiBootManagerBoot (
     //
     // 4. Repair system through DriverHealth protocol
     //
-    BmRepairAllControllers ();
+    BmRepairAllControllers (0);
   }
 
   PERF_START_EX (gImageHandle, "BdsAttempt", NULL, 0, (UINT32) OptionNumber);
diff --git a/MdeModulePkg/Library/UefiBootManagerLib/BmDriverHealth.c b/MdeModulePkg/Library/UefiBootManagerLib/BmDriverHealth.c
index ddcee8b0676f..db2f859ae73d 100644
--- a/MdeModulePkg/Library/UefiBootManagerLib/BmDriverHealth.c
+++ b/MdeModulePkg/Library/UefiBootManagerLib/BmDriverHealth.c
@@ -423,10 +423,13 @@ EfiBootManagerFreeDriverHealthInfo (
 
 /**
   Repair all the controllers according to the Driver Health status queried.
+
+  @param ReconnectRepairCount     To record the number of recursive call of
+                                  this function itself.
 **/
 VOID
 BmRepairAllControllers (
-  VOID
+  UINTN       ReconnectRepairCount
   )
 {
   EFI_STATUS                          Status;
@@ -548,10 +551,6 @@ BmRepairAllControllers (
   EfiBootManagerFreeDriverHealthInfo (DriverHealthInfo, Count);
 
 
-  if (ReconnectRequired) {
-    BmRepairAllControllers ();
-  }
-
   DEBUG_CODE (
     CHAR16 *ControllerName;
 
@@ -576,6 +575,15 @@ BmRepairAllControllers (
     EfiBootManagerFreeDriverHealthInfo (DriverHealthInfo, Count);
     );
 
+  if (ReconnectRequired) {
+    if (ReconnectRepairCount < MAX_RECONNECT_REPAIR) {
+      BmRepairAllControllers (ReconnectRepairCount + 1);
+    } else {
+      DEBUG ((DEBUG_ERROR, "[%a:%d] Repair failed after %d retries.\n",
+        __FUNCTION__, __LINE__, ReconnectRepairCount));
+    }
+  }
+
   if (RebootRequired) {
     DEBUG ((EFI_D_INFO, "[BDS] One of the Driver Health instances requires rebooting.\n"));
     gRT->ResetSystem (EfiResetWarm, EFI_SUCCESS, 0, NULL);
-- 
2.7.4