[jdk17u-dev] RFR: 8312065: Socket.connect does not timeout when profiling [v7]

[Long Yang]

> Hi all,
> 
> This pull request contains a fix for [JDK-8312065](https://bugs.openjdk.org/browse/JDK-8312065).
> 
> The old SocketImpl is still present in JDK 17, can be enabled with -Djdk.net.usePlainSocketImpl.
> 
> I have verified that this problem exists on Linux and macOS, and I feel that it also exists on AIX, 
> so I repaired these 3 platforms. Windows implementations are different, so don't have this problem.
> 
> All callers of NET_Poll() already check for EINTR, so the fix is to remove do-while loop in the implementation of NET_Poll().
> 
> Other methods, such as NET_Read, NET_NonBlockingRead, NET_Accept, NET_Connect, are not affected.
> Because if Socket has timeout, it will call NET_Timeout first, and then call them. NET_Timeout has a correct timeout implementation and is not affected by profiling signals.
> If the Socket does not have a timeout, and if the system call is interrupted by a signal, the [Linux Kernel will automatically retry](https://man7.org/linux/man-pages/man7/signal.7.html), and the application code will not be aware of it.
> 
> Thanks!

Long Yang has updated the pull request incrementally with one additional commit since the last revision:

  update comments

-------------

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/1639/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/1639/files/81ea1742..db56a210

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1639&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1639&range=05-06

  Stats: 6 lines in 3 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1639.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1639/head:pull/1639

PR: https://git.openjdk.org/jdk17u-dev/pull/1639