On 01/19/2017 08:35 AM, Lino Sanfilippo wrote:
Hi,
altek/rtlwifi/rtl8192ce/hw.c
b/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/hw.c
index a47be73..143766c4 100644
--- a/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/hw.c
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192ce/hw.c
@@ -1306,9 +1306,9 @@ void rtl92ce_enable_interrupt(struct ieee80211_hw *hw)
struct rtl_priv *rtlpriv = rtl_priv(hw);
struct rtl_pci *rtlpci = rtl_pcidev(rtl_pcipriv(hw));
+ rtlpci->irq_enabled = true;
rtl_write_dword(rtlpriv, REG_HIMR, rtlpci->irq_mask[0] & 0xFFFFFFFF);
rtl_write_dword(rtlpriv, REG_HIMRE, rtlpci->irq_mask[1] & 0xFFFFFFFF);
- rtlpci->irq_enabled = true;
}
void rtl92ce_disable_interrupt(struct ieee80211_hw *hw)
@@ -1316,9 +1316,9 @@ void rtl92ce_disable_interrupt(struct ieee80211_hw *hw)
struct rtl_priv *rtlpriv = rtl_priv(hw);
struct rtl_pci *rtlpci = rtl_pcidev(rtl_pcipriv(hw));
+ rtlpci->irq_enabled = false;
rtl_write_dword(rtlpriv, REG_HIMR, IMR8190_DISABLED);
rtl_write_dword(rtlpriv, REG_HIMRE, IMR8190_DISABLED);
- rtlpci->irq_enabled = false;
}
AFAIK you also have to use memory barriers here to ensure that
the concerning instructions are not reordered, and both irq handler
and process have a consistent perception of irq_enabled, e.g:
rtlpci->irq_enabled = true;
smp_wmb();
rtl_write_dword(rtlpriv, REG_HIMR, rtlpci->irq_mask[0] & 0xFFFFFFFF);
and in the irq handler
if (rtlpci->irq_enabled == 0) {
smp_rmb();
return ret;
}
I can see the potential race condition between setting interrupts and setting
the flag, and I will likely accept Bharat's patch after testing.
I am likely displaying my ignorance regarding instruction reordering, but what
compiler/cpu combination is likely to move a simple set operation after a call
to an external routine? Is the smp_wmb() operation really needed? I am also
unsure of the smp_rmb() call in the interrupt handler. Neither instruction
should cause any problems, but I'm not sure they are needed.
Larry
