net: ethernet: ti: cpdma: fix lockup in cpdma_ctlr_destroy()

BugLink: http://bugs.launchpad.net/bugs/1625177
Fix deadlock in cpdma_ctlr_destroy() which is triggered now on
cpsw module removal:
 cpsw_remove()
 - cpdma_ctlr_destroy()
   - spin_lock_irqsave(&ctlr->lock, flags)
   - cpdma_ctlr_stop()
     - spin_lock_irqsave(&ctlr->lock, flags);
   - cpdma_chan_destroy()
     - spin_lock_irqsave(&ctlr->lock, flags);

The issue has not been observed before because CPDMA channels have
been destroyed manually by CPSW until commit d941ebe88a41 ("net:
ethernet: ti: cpsw: use destroy ctlr to destroy channels") was merged.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit fccd5badb84de03fef9b072e7ae72fe0ea8348e3)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
index 657b65bf5cac64254b4db7c845038d2e40549a8c..ba99617fbfbacafa2895339aa470a19c1d330d12 100644 (file)
--- a/drivers/net/ethernet/ti/davinci_cpdma.c
+++ b/drivers/net/ethernet/ti/davinci_cpdma.c
@@ -442,13 +442,11 @@ EXPORT_SYMBOL_GPL(cpdma_ctlr_dump);
 
 int cpdma_ctlr_destroy(struct cpdma_ctlr *ctlr)
 {
-       unsigned long flags;
        int ret = 0, i;
 
        if (!ctlr)
                return -EINVAL;
 
-       spin_lock_irqsave(&ctlr->lock, flags);
        if (ctlr->state != CPDMA_STATE_IDLE)
                cpdma_ctlr_stop(ctlr);
 
@@ -456,7 +454,6 @@ int cpdma_ctlr_destroy(struct cpdma_ctlr *ctlr)
                cpdma_chan_destroy(ctlr->channels[i]);
 
        cpdma_desc_pool_destroy(ctlr->pool);
-       spin_unlock_irqrestore(&ctlr->lock, flags);
        return ret;
 }
 EXPORT_SYMBOL_GPL(cpdma_ctlr_destroy);