mainlining shenanigans
0f62aeec0f
Vladimir Zapolskiy says: ==================== ravb/sh_eth: fix sleep in atomic by reusing shared ethtool handlers For ages trivial changes to RAVB and SuperH ethernet links by means of standard 'ethtool' trigger a 'sleeping function called from invalid context' bug, to visualize it on r8a7795 ULCB: % ethtool -r eth0 BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747 in_atomic(): 1, irqs_disabled(): 128, pid: 554, name: ethtool INFO: lockdep is turned off. irq event stamp: 0 hardirqs last enabled at (0): [<0000000000000000>] (null) hardirqs last disabled at (0): [<ffff0000080e1d3c>] copy_process.isra.7.part.8+0x2cc/0x1918 softirqs last enabled at (0): [<ffff0000080e1d3c>] copy_process.isra.7.part.8+0x2cc/0x1918 softirqs last disabled at (0): [<0000000000000000>] (null) CPU: 5 PID: 554 Comm: ethtool Not tainted 4.17.0-rc4-arm64-renesas+ #33 Hardware name: Renesas H3ULCB board based on r8a7795 ES2.0+ (DT) Call trace: dump_backtrace+0x0/0x198 show_stack+0x24/0x30 dump_stack+0xb8/0xf4 ___might_sleep+0x1c8/0x1f8 __might_sleep+0x58/0x90 __mutex_lock+0x50/0x890 mutex_lock_nested+0x3c/0x50 phy_start_aneg_priv+0x38/0x180 phy_start_aneg+0x24/0x30 ravb_nway_reset+0x3c/0x68 dev_ethtool+0x3dc/0x2338 dev_ioctl+0x19c/0x490 sock_do_ioctl+0xe0/0x238 sock_ioctl+0x254/0x460 do_vfs_ioctl+0xb0/0x918 ksys_ioctl+0x50/0x80 sys_ioctl+0x34/0x48 __sys_trace_return+0x0/0x4 The root cause is that an attempt to modify ECMR and GECMR registers only when RX/TX function is disabled was too overcomplicated in its original implementation, also processing of an optional Link Change interrupt added even more complexity, as a result the implementation was error prone. The new locking scheme is confirmed to be correct by dumping driver specific and generic PHY framework function calls with aid of ftrace while running more or less advanced tests. Please note that sh_eth patches from the series were built-tested only. On purpose I do not add Fixes tags, the reused PHY handlers were added way later than the fixed problems were firstly found in the drivers. Changes from v1 to v2: * the original patches are split to bugfixes and enhancements only, both v1 and v2 series are absolutely equal in total, thus I omit description of changes in individual patches, * the latter implies that there should be no strict need for retesting, but because formally two series are different, I have to drop the tags given by Geert and Andrew, please send your tags again. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.