Messages in this thread | | | Subject | Re: [PATCH i2c/slave-mqueue v5] i2c: slave-mqueue: add a slave backend to receive and queue messages | From | "Wang, Haiyue" <> | Date | Thu, 30 May 2019 09:39:05 +0800 |
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在 2019-05-30 07:11, Eduardo Valentin 写道: >>> this code goes access and modify data here, e.g. msg->len and msg->buf. >>> >>> On this case (I2C_SLAVE_WRITE_RECEIVED), this code wont protect access. >>> >>> This can cause concurrence issues if you receive an IRQ when the user >>> is on your bin_read(). >> User will not touch 'msg = mq->curr;', just touch 'msg = >> &mq->queue[mq->out];' > What happens if mq->curr == mq->queue[mq->out]? > 1. The Read will check.
+ spin_lock_irqsave(&mq->lock, flags); + if (mq->out != mq->in) { + msg = &mq->queue[mq->out];
2. Flush the oldeast message. ^_^
+ case I2C_SLAVE_STOP: + if (unlikely(mq->truncated || msg->len < 2)) + break; + + spin_lock(&mq->lock); + mq->in = MQ_QUEUE_NEXT(mq->in); + mq->curr = &mq->queue[mq->in]; + mq->curr->len = 0; + + /* Flush the oldest message */ + if (mq->out == mq->in) + mq->out = MQ_QUEUE_NEXT(mq->out); + spin_unlock(&mq->lock);
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