# git rev-parse -q --verify a5b9b743fdb653c37d347b303fb60dff0c743f7e^{commit}
a5b9b743fdb653c37d347b303fb60dff0c743f7e
already have revision, skipping fetch
# git checkout -q -f -B kisskb a5b9b743fdb653c37d347b303fb60dff0c743f7e
# git clean -qxdf
# < git log -1
# commit a5b9b743fdb653c37d347b303fb60dff0c743f7e
# Author: Frederic Barrat <fbarrat@linux.ibm.com>
# Date:   Mon Jun 24 16:41:48 2019 +0200
# 
#     ocxl: Fix concurrent AFU open and device removal
#     
#     If an ocxl device is unbound through sysfs at the same time its AFU is
#     being opened by a user process, the open code may dereference freed
#     stuctures, which can lead to kernel oops messages. You'd have to hit a
#     tiny time window, but it's possible. It's fairly easy to test by
#     making the time window bigger artificially.
#     
#     Fix it with a combination of 2 changes:
#       - when an AFU device is found in the IDR by looking for the device
#         minor number, we should hold a reference on the device until after
#         the context is allocated. A reference on the AFU structure is kept
#         when the context is allocated, so we can release the reference on
#         the device after the context allocation.
#       - with the fix above, there's still another even tinier window,
#         between the time the AFU device is found in the IDR and the
#         reference on the device is taken. We can fix this one by removing
#         the IDR entry earlier, when the device setup is removed, instead
#         of waiting for the 'release' device callback. With proper locking
#         around the IDR.
#     
#     Fixes: 75ca758adbaf ("ocxl: Create a clear delineation between ocxl backend & frontend")
#     Cc: stable@vger.kernel.org # v5.2+
#     Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
#     Reviewed-by: Greg Kurz <groug@kaod.org>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/20190624144148.32022-1-fbarrat@linux.ibm.com
# < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-gcc --version
# < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-ld --version
# < git log --format=%s --max-count=1 a5b9b743fdb653c37d347b303fb60dff0c743f7e
# < make -s -j 80 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-  mmu_defconfig
# make -s -j 80 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-  
Kernel: arch/microblaze/boot/linux.bin is ready  (#1)
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_mmu_defconfig_microblaze
# Build took: 0:00:52.829396