e1000e: debug contention on NVM SWFLAG
This patch adds a mutex to the e1000e driver that would help
catch any collisions of two e1000e threads accessing hardware
at the same time.
description and patch updated by Jesse
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/net/e1000e/ich8lan.c b/drivers/net/e1000e/ich8lan.c
index f4b6744..0b6095b 100644
--- a/drivers/net/e1000e/ich8lan.c
+++ b/drivers/net/e1000e/ich8lan.c
@@ -380,6 +380,9 @@
return 0;
}
+static DEFINE_MUTEX(nvm_mutex);
+static pid_t nvm_owner = -1;
+
/**
* e1000_acquire_swflag_ich8lan - Acquire software control flag
* @hw: pointer to the HW structure
@@ -393,6 +396,15 @@
u32 extcnf_ctrl;
u32 timeout = PHY_CFG_TIMEOUT;
+ WARN_ON(preempt_count());
+
+ if (!mutex_trylock(&nvm_mutex)) {
+ WARN(1, KERN_ERR "e1000e mutex contention. Owned by pid %d\n",
+ nvm_owner);
+ mutex_lock(&nvm_mutex);
+ }
+ nvm_owner = current->pid;
+
while (timeout) {
extcnf_ctrl = er32(EXTCNF_CTRL);
extcnf_ctrl |= E1000_EXTCNF_CTRL_SWFLAG;
@@ -407,6 +419,8 @@
if (!timeout) {
hw_dbg(hw, "FW or HW has locked the resource for too long.\n");
+ nvm_owner = -1;
+ mutex_unlock(&nvm_mutex);
return -E1000_ERR_CONFIG;
}
@@ -428,6 +442,9 @@
extcnf_ctrl = er32(EXTCNF_CTRL);
extcnf_ctrl &= ~E1000_EXTCNF_CTRL_SWFLAG;
ew32(EXTCNF_CTRL, extcnf_ctrl);
+
+ nvm_owner = -1;
+ mutex_unlock(&nvm_mutex);
}
/**
