Jann Horn b987222654 tracing: Fix buffer_ref pipe ops ... This fixes multiple issues in buffer_pipe_buf_ops: - The ->steal() handler must not return zero unless the pipe buffer has the only reference to the page. But generic_pipe_buf_steal() assumes that every reference to the pipe is tracked by the page's refcount, which isn't true for these buffers - buffer_pipe_buf_get(), which duplicates a buffer, doesn't touch the page's refcount. Fix it by using generic_pipe_buf_nosteal(), which refuses every attempted theft. It should be easy to actually support ->steal, but the only current users of pipe_buf_steal() are the virtio console and FUSE, and they also only use it as an optimization. So it's probably not worth the effort. - The ->get() and ->release() handlers can be invoked concurrently on pipe buffers backed by the same struct buffer_ref. Make them safe against concurrency by using refcount_t. - The pointers stored in ->private were only zeroed out when the last reference to the buffer_ref was dropped. As far as I know, this shouldn't be necessary anyway, but if we do it, let's always do it. Link: http://lkml.kernel.org/r/20190404215925.253531-1-jannh@google.com Cc: Ingo Molnar <mingo@redhat.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org Fixes: 73a757e631 ("ring-buffer: Return reader page back into existing ring buffer") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>		2019-04-26 11:44:39 -04:00
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acpi	ACPI: use different default debug value than ACPICA	2019-03-25 10:45:59 +01:00
asm-generic
clocksource
crypto
drm
dt-bindings
keys
kvm
linux	tracing: Fix buffer_ref pipe ops	2019-04-26 11:44:39 -04:00
math-emu
media
memory
misc
net
pcmcia
ras
rdma
scsi
soc
sound
target
trace
uapi	A collection of x86 and ARM bugfixes, and some improvements to documentation.	2019-03-31 08:55:59 -07:00
video
xen