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| author | Vaibhav Jain <vaibhav@linux.vnet.ibm.com> | 2016-10-14 15:08:36 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-10-28 03:45:28 -0400 |
| commit | 627da03975badd33d66197dfab79932e566238be (patch) | |
| tree | 7794545713470e4a271d39a590eead49fb136bca /Documentation | |
| parent | ee13e8a1ae2f2ed434bdcc24011bd722fb3b32d9 (diff) | |
| download | lwn-627da03975badd33d66197dfab79932e566238be.tar.gz lwn-627da03975badd33d66197dfab79932e566238be.zip | |
cxl: Prevent adapter reset if an active context exists
commit 70b565bbdb911023373e035225ab10077e4ab937 upstream.
This patch prevents resetting the cxl adapter via sysfs in presence of
one or more active cxl_context on it. This protects against an
unrecoverable error caused by PSL owning a dirty cache line even after
reset and host tries to touch the same cache line. In case a force reset
of the card is required irrespective of any active contexts, the int
value -1 can be stored in the 'reset' sysfs attribute of the card.
The patch introduces a new atomic_t member named contexts_num inside
struct cxl that holds the number of active context attached to the card
, which is checked against '0' before proceeding with the reset. To
prevent against a race condition where a context is activated just after
reset check is performed, the contexts_num is atomically set to '-1'
after reset-check to indicate that no more contexts can be activated on
the card anymore.
Before activating a context we atomically test if contexts_num is
non-negative and if so, increment its value by one. In case the value of
contexts_num is negative then it indicates that the card is about to be
reset and context activation is error-ed out at that point.
Fixes: 62fa19d4b4fd ("cxl: Add ability to reset the card")
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-cxl | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-cxl b/Documentation/ABI/testing/sysfs-class-cxl index 4ba0a2a61926..640f65e79ef1 100644 --- a/Documentation/ABI/testing/sysfs-class-cxl +++ b/Documentation/ABI/testing/sysfs-class-cxl @@ -220,8 +220,11 @@ What: /sys/class/cxl/<card>/reset Date: October 2014 Contact: linuxppc-dev@lists.ozlabs.org Description: write only - Writing 1 will issue a PERST to card which may cause the card - to reload the FPGA depending on load_image_on_perst. + Writing 1 will issue a PERST to card provided there are no + contexts active on any one of the card AFUs. This may cause + the card to reload the FPGA depending on load_image_on_perst. + Writing -1 will do a force PERST irrespective of any active + contexts on the card AFUs. Users: https://github.com/ibm-capi/libcxl What: /sys/class/cxl/<card>/perst_reloads_same_image (not in a guest) |