/* Tom Kelly's Scalable TCP * * See http://www.deneholme.net/tom/scalable/ * * John Heffner */ #include #include /* These factors derived from the recommended values in the aer: * .01 and and 7/8. We use 50 instead of 100 to account for * delayed ack. */ #define TCP_SCALABLE_AI_CNT 50U #define TCP_SCALABLE_MD_SCALE 3 struct scalable { u32 loss_cwnd; }; static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked) { struct tcp_sock *tp = tcp_sk(sk); if (!tcp_is_cwnd_limited(sk)) return; if (tcp_in_slow_start(tp)) tcp_slow_start(tp, acked); else tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT), 1); } static u32 tcp_scalable_ssthresh(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); struct scalable *ca = inet_csk_ca(sk); ca->loss_cwnd = tp->snd_cwnd; return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U); } static u32 tcp_scalable_cwnd_undo(struct sock *sk) { const struct scalable *ca = inet_csk_ca(sk); return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd); } static struct tcp_congestion_ops tcp_scalable __read_mostly = { .ssthresh = tcp_scalable_ssthresh, .undo_cwnd = tcp_scalable_cwnd_undo, .cong_avoid = tcp_scalable_cong_avoid, .owner = THIS_MODULE, .name = "scalable", }; static int __init tcp_scalable_register(void) { return tcp_register_congestion_control(&tcp_scalable); } static void __exit tcp_scalable_unregister(void) { tcp_unregister_congestion_control(&tcp_scalable); } module_init(tcp_scalable_register); module_exit(tcp_scalable_unregister); MODULE_AUTHOR("John Heffner"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("Scalable TCP"); /drivers/usb/gadget/udc/trace.h'>logtreecommitdiff
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authorIago Abal <mail@iagoabal.eu>2017-01-11 14:00:21 +0100
committerVinod Koul <vinod.koul@intel.com>2017-01-25 15:35:11 +0530
commit91539eb1fda2d530d3b268eef542c5414e54bf1a (patch)
tree960f5ca6342ad20837aff18aad6e8ecd7da32fd6 /drivers/usb/gadget/udc/trace.h
parent6610d0edf6dc7ee97e46ab3a538a565c79d26199 (diff)
dmaengine: pl330: fix double lock
The static bug finder EBA (http://www.iagoabal.eu/eba/) reported the following double-lock bug: Double lock: 1. spin_lock_irqsave(pch->lock, flags) at pl330_free_chan_resources:2236; 2. call to function `pl330_release_channel' immediately after; 3. call to function `dma_pl330_rqcb' in line 1753; 4. spin_lock_irqsave(pch->lock, flags) at dma_pl330_rqcb:1505. I have fixed it as suggested by Marek Szyprowski. First, I have replaced `pch->lock' with `pl330->lock' in functions `pl330_alloc_chan_resources' and `pl330_free_chan_resources'. This avoids the double-lock by acquiring a different lock than `dma_pl330_rqcb'. NOTE that, as a result, `pl330_free_chan_resources' executes `list_splice_tail_init' on `pch->work_list' under lock `pl330->lock', whereas in the rest of the code `pch->work_list' is protected by `pch->lock'. I don't know if this may cause race conditions. Similarly `pch->cyclic' is written by `pl330_alloc_chan_resources' under `pl330->lock' but read by `pl330_tx_submit' under `pch->lock'. Second, I have removed locking from `pl330_request_channel' and `pl330_release_channel' functions. Function `pl330_request_channel' is only called from `pl330_alloc_chan_resources', so the lock is already held. Function `pl330_release_channel' is called from `pl330_free_chan_resources', which already holds the lock, and from `pl330_del'. Function `pl330_del' is called in an error path of `pl330_probe' and at the end of `pl330_remove', but I assume that there cannot be concurrent accesses to the protected data at those points. Signed-off-by: Iago Abal <mail@iagoabal.eu> Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/usb/gadget/udc/trace.h')