From 79ffe6087e9145d2377385cac48d0d6a6b4225a5 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 5 Nov 2019 14:24:35 -0800 Subject: net/tls: add a TX lock TLS TX needs to release and re-acquire the socket lock if send buffer fills up. TLS SW TX path currently depends on only allowing one thread to enter the function by the abuse of sk_write_pending. If another writer is already waiting for memory no new ones are allowed in. This has two problems: - writers don't wake other threads up when they leave the kernel; meaning that this scheme works for single extra thread (second application thread or delayed work) because memory becoming available will send a wake up request, but as Mallesham and Pooja report with larger number of threads it leads to threads being put to sleep indefinitely; - the delayed work does not get _scheduled_ but it may _run_ when other writers are present leading to crashes as writers don't expect state to change under their feet (same records get pushed and freed multiple times); it's hard to reliably bail from the work, however, because the mere presence of a writer does not guarantee that the writer will push pending records before exiting. Ensuring wakeups always happen will make the code basically open code a mutex. Just use a mutex. The TLS HW TX path does not have any locking (not even the sk_write_pending hack), yet it uses a per-socket sg_tx_data array to push records. Fixes: a42055e8d2c3 ("net/tls: Add support for async encryption of records for performance") Reported-by: Mallesham Jatharakonda Reported-by: Pooja Trivedi Signed-off-by: Jakub Kicinski Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- include/net/tls.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/net/tls.h') diff --git a/include/net/tls.h b/include/net/tls.h index c664e6dba0d1..794e297483ea 100644 --- a/include/net/tls.h +++ b/include/net/tls.h @@ -40,6 +40,7 @@ #include #include #include +#include #include #include @@ -269,6 +270,10 @@ struct tls_context { bool in_tcp_sendpages; bool pending_open_record_frags; + + struct mutex tx_lock; /* protects partially_sent_* fields and + * per-type TX fields + */ unsigned long flags; /* cache cold stuff */ -- cgit v1.2.3-59-g8ed1b