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Lennert Buytenhek 7c1ddcee53 igc: Reinstate IGC_REMOVED logic and implement it properly 
The initially merged version of the igc driver code (via commit
146740f9ab, "igc: Add support for PF") contained the following
IGC_REMOVED checks in the igc_rd32/wr32() MMIO accessors:

	u32 igc_rd32(struct igc_hw *hw, u32 reg)
	{
		u8 __iomem *hw_addr = READ_ONCE(hw->hw_addr);
		u32 value = 0;

		if (IGC_REMOVED(hw_addr))
			return ~value;

		value = readl(&hw_addr[reg]);

		/* reads should not return all F's */
		if (!(~value) && (!reg || !(~readl(hw_addr))))
			hw->hw_addr = NULL;

		return value;
	}

And:

	#define wr32(reg, val) \
	do { \
		u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \
		if (!IGC_REMOVED(hw_addr)) \
			writel((val), &hw_addr[(reg)]); \
	} while (0)

E.g. igb has similar checks in its MMIO accessors, and has a similar
macro E1000_REMOVED, which is implemented as follows:

	#define E1000_REMOVED(h) unlikely(!(h))

These checks serve to detect and take note of an 0xffffffff MMIO read
return from the device, which can be caused by a PCIe link flap or some
other kind of PCI bus error, and to avoid performing MMIO reads and
writes from that point onwards.

However, the IGC_REMOVED macro was not originally implemented:

	#ifndef IGC_REMOVED
	#define IGC_REMOVED(a) (0)
	#endif /* IGC_REMOVED */

This led to the IGC_REMOVED logic to be removed entirely in a
subsequent commit (commit 3c215fb18e, "igc: remove IGC_REMOVED
function"), with the rationale that such checks matter only for
virtualization and that igc does not support virtualization -- but a
PCIe device can become detached even without virtualization being in
use, and without proper checks, a PCIe bus error affecting an igc
adapter will lead to various NULL pointer dereferences, as the first
access after the error will set hw->hw_addr to NULL, and subsequent
accesses will blindly dereference this now-NULL pointer.

This patch reinstates the IGC_REMOVED checks in igc_rd32/wr32(), and
implements IGC_REMOVED the way it is done for igb, by checking for the
unlikely() case of hw_addr being NULL.  This change prevents the oopses
seen when a PCIe link flap occurs on an igc adapter.

Fixes: 146740f9ab ("igc: Add support for PF")
Signed-off-by: Lennert Buytenhek <buytenh@arista.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
2022-07-14 09:18:02 -07:00
arch OpenRISC fixes for 5.19-rc5 2022-07-06 10:10:26 -07:00
block block: remove WARN_ON() from bd_link_disk_holder 2022-06-23 07:48:05 -06:00
certs Certs changes 2022-06-21 12:13:53 -05:00
crypto crypto: s390 - do not depend on CRYPTO_HW for SIMD implementations 2022-07-06 20:04:06 -07:00
Documentation A small set of fixes for 2022-07-13 14:27:38 +01:00
drivers igc: Reinstate IGC_REMOVED logic and implement it properly 2022-07-14 09:18:02 -07:00
fs Fixes for 5.19-rc5: 2022-07-03 09:42:17 -07:00
include A small set of fixes for 2022-07-13 14:27:38 +01:00
init gcc-12: disable '-Warray-bounds' universally for now 2022-06-09 10:11:12 -07:00
ipc These changes update the ipc sysctls so that they are fundamentally 2022-06-03 15:54:57 -07:00
kernel sysctl: Fix data-races in proc_dointvec_ms_jiffies(). 2022-07-13 12:56:49 +01:00
lib lockref: remove unused 'lockref_get_or_lock()' function 2022-07-03 14:40:28 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Minor things, mainly - mailmap updates, MAINTAINERS updates, etc. 2022-06-26 14:00:55 -07:00
net ip: fix dflt addr selection for connected nexthop 2022-07-14 14:41:19 +02:00
samples fprobe, samples: Add module parameter descriptions 2022-06-24 15:23:04 -07:00
scripts kbuild: Ignore __this_module in gen_autoksyms.sh 2022-06-26 06:15:05 +09:00
security selinux: free contexts previously transferred in selinux_add_opt() 2022-06-15 21:20:45 -04:00
sound ALSA: cs46xx: Fix missing snd_card_free() call at probe error 2022-07-05 17:24:05 +02:00
tools selftests/net: test nexthop without gw 2022-07-14 14:41:19 +02:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: x86: disable preemption around the call to kvm_arch_vcpu_{un|}blocking 2022-06-09 10:52:20 -04:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap mailmap: add entry for Christian Marangi 2022-06-16 19:11:32 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 5.19-rc6, including fixes from bpf, netfilter, 2022-07-07 10:08:20 -07:00
Makefile Linux 5.19-rc5 2022-07-03 15:39:28 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.

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.