On 4/7/20 7:33 AM, Manivannan Sadhasivam wrote:
Hi Dan,
On Tue, Apr 07, 2020 at 04:55:59PM +0300, Dan Carpenter wrote:
Hello Manivannan Sadhasivam,
The patch 189ff97cca53: "bus: mhi: core: Add support for data
transfer" from Feb 20, 2020, leads to the following static checker
warning:
drivers/bus/mhi/core/main.c:1153 mhi_queue_buf()
error: double locked 'mhi_chan->lock' (orig line 1110)
drivers/bus/mhi/core/main.c
1142 }
1143
1144 /* Toggle wake to exit out of M2 */
1145 mhi_cntrl->wake_toggle(mhi_cntrl);
1146
1147 if (mhi_chan->dir == DMA_TO_DEVICE)
1148 atomic_inc(&mhi_cntrl->pending_pkts);
1149
1150 if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl))) {
1151 unsigned long flags;
1152
1153 read_lock_irqsave(&mhi_chan->lock, flags);
parse_xfer_event is taking read lock : read_lock_bh(&mhi_chan->lock);
first and later
mhi_queue_buf takes read lock: read_lock_irqsave(&mhi_chan->lock, flags);
Both are read locks which are recursive, is this problematic ?
^^^^^^^^^^^^^^^
The caller is already holding this lock.
Hmm. We have one internal user of this function and that's where the locking
has gone wrong. Will fix it.
Thanks for reporting!
Regards,
Mani
1154 mhi_ring_chan_db(mhi_cntrl, mhi_chan);
1155 read_unlock_irqrestore(&mhi_chan->lock, flags);
1156 }
1157
1158 read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);
1159
1160 return 0;
1161 }
1162 EXPORT_SYMBOL_GPL(mhi_queue_buf);
regards,
dan carpenter
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