From ca9c90ba09ca3c9799319f46a56f397afbf617c2 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Sun, 4 Oct 2009 10:15:40 -0300 Subject: [PATCH] i7core_edac: Use a lockless ringbuffer Signed-off-by: Mauro Carvalho Chehab --- drivers/edac/i7core_edac.c | 83 +++++++++++++++++++++++++------------- 1 file changed, 55 insertions(+), 28 deletions(-) diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c index 97f6d1759c99..94aeca011ac4 100644 --- a/drivers/edac/i7core_edac.c +++ b/drivers/edac/i7core_edac.c @@ -28,7 +28,6 @@ #include #include #include -#include #include #include @@ -239,9 +238,16 @@ struct i7core_pvt { /* mcelog glue */ struct edac_mce edac_mce; + + /* Fifo double buffers */ struct mce mce_entry[MCE_LOG_LEN]; - unsigned mce_count; - spinlock_t mce_lock; + struct mce mce_outentry[MCE_LOG_LEN]; + + /* Fifo in/out counters */ + unsigned mce_in, mce_out; + + /* Count indicator to show errors not got */ + unsigned mce_overrun; }; /* Static vars */ @@ -1617,30 +1623,50 @@ static void i7core_check_error(struct mem_ctl_info *mci) struct i7core_pvt *pvt = mci->pvt_info; int i; unsigned count = 0; - struct mce *m = NULL; - unsigned long flags; + struct mce *m; - /* Copy all mce errors into a temporary buffer */ - spin_lock_irqsave(&pvt->mce_lock, flags); - if (pvt->mce_count) { - m = kmalloc(sizeof(*m) * pvt->mce_count, GFP_ATOMIC); + /* + * MCE first step: Copy all mce errors into a temporary buffer + * We use a double buffering here, to reduce the risk of + * loosing an error. + */ + smp_rmb(); + count = (pvt->mce_out + sizeof(mce_entry) - pvt->mce_in) + % sizeof(mce_entry); + if (!count) + return; - if (m) { - count = pvt->mce_count; - memcpy(m, &pvt->mce_entry, sizeof(*m) * count); - } - pvt->mce_count = 0; - } + m = pvt->mce_outentry; + if (pvt->mce_in + count > sizeof(mce_entry)) { + unsigned l = sizeof(mce_entry) - pvt->mce_in; - spin_unlock_irqrestore(&pvt->mce_lock, flags); + memcpy(m, &pvt->mce_entry[pvt->mce_in], sizeof(*m) * l); + smp_wmb(); + pvt->mce_in = 0; + count -= l; + m += l; + } + memcpy(m, &pvt->mce_entry[pvt->mce_in], sizeof(*m) * count); + smp_wmb(); + pvt->mce_in += count; + + smp_rmb(); + if (pvt->mce_overrun) { + i7core_printk(KERN_ERR, "Lost %d memory errors\n", + pvt->mce_overrun); + smp_wmb(); + pvt->mce_overrun = 0; + } - /* proccess mcelog errors */ + /* + * MCE second step: parse errors and display + */ for (i = 0; i < count; i++) - i7core_mce_output_error(mci, &m[i]); + i7core_mce_output_error(mci, &pvt->mce_outentry[i]); - kfree(m); - - /* check memory count errors */ + /* + * Now, let's increment CE error counts + */ if (!pvt->is_registered) i7core_udimm_check_mc_ecc_err(mci); else @@ -1657,7 +1683,6 @@ static int i7core_mce_check_error(void *priv, struct mce *mce) { struct mem_ctl_info *mci = priv; struct i7core_pvt *pvt = mci->pvt_info; - unsigned long flags; /* * Just let mcelog handle it if the error is @@ -1679,12 +1704,15 @@ static int i7core_mce_check_error(void *priv, struct mce *mce) return 0; } - spin_lock_irqsave(&pvt->mce_lock, flags); - if (pvt->mce_count < MCE_LOG_LEN) { - memcpy(&pvt->mce_entry[pvt->mce_count], mce, sizeof(*mce)); - pvt->mce_count++; + smp_rmb(); + if ((pvt->mce_out + 1) % sizeof(mce_entry) == pvt->mce_in) { + smp_wmb(); + pvt->mce_overrun++; + return 0; } - spin_unlock_irqrestore(&pvt->mce_lock, flags); + smp_wmb(); + pvt->mce_out = (pvt->mce_out + 1) % sizeof(mce_entry); + memcpy(&pvt->mce_entry[pvt->mce_out], mce, sizeof(*mce)); /* Handle fatal errors immediately */ if (mce->mcgstatus & 1) @@ -1777,7 +1805,6 @@ static int i7core_register_mci(struct i7core_dev *i7core_dev, /* Registers on edac_mce in order to receive memory errors */ pvt->edac_mce.priv = mci; pvt->edac_mce.check_error = i7core_mce_check_error; - spin_lock_init(&pvt->mce_lock); rc = edac_mce_register(&pvt->edac_mce); if (unlikely(rc < 0)) { -- 2.39.2