Gleb Smirnoff 08d9c92027 tcp_input/syncache: acquire only read lock on PCB for SYN,!ACK packets ... When packet is a SYN packet, we don't need to modify any existing PCB. Normally SYN arrives on a listening socket, we either create a syncache entry or generate syncookie, but we don't modify anything with the listening socket or associated PCB. Thus create a new PCB lookup mode - rlock if listening. This removes the primary contention point under SYN flood - the listening socket PCB. Sidenote: when SYN arrives on a synchronized connection, we still don't need write access to PCB to send a challenge ACK or just to drop. There is only one exclusion - tcptw recycling. However, existing entanglement of tcp_input + stacks doesn't allow to make this change small. Consider this patch as first approach to the problem. Reviewed by: rrs Differential revision: https://reviews.freebsd.org/D29576		2021-04-12 08:25:31 -07:00
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mac_audit.c
mac_cred.c
mac_framework.c
mac_framework.h
mac_inet.c	tcp_input/syncache: acquire only read lock on PCB for SYN,!ACK packets	2021-04-12 08:25:31 -07:00
mac_inet6.c
mac_internal.h
mac_label.c
mac_net.c
mac_pipe.c
mac_policy.h
mac_posix_sem.c
mac_posix_shm.c
mac_priv.c
mac_process.c
mac_socket.c
mac_syscalls.c
mac_system.c
mac_sysv_msg.c
mac_sysv_sem.c
mac_sysv_shm.c
mac_vfs.c