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b2326338dc
Ravi reports that statfs() may be called by unprivileged users on the
efivarfs mount point, which may result in a flood of calls to the
QueryVariableInfo() runtime service. These calls are disproportionately
costly on x86 systems where the variable store is backed by SMM, as each
SMM entry requires a rendez-vous of all the CPUs.
So rate limit the calls to QueryVariableInfo() at twice per second, and
return the most recently obtained value for calls that are elided.
Cc: <stable@vger.kernel.org>
Reported-by: Ravi Bangoria <ravi.bangoria@amd.com>
Fixes: d86ff3333c ("efivarfs: expose used and total size")
Reviewed-by: Anisse Astier <anisse@astier.eu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
571 lines
13 KiB
571 lines
13 KiB