As other exported fifo functions, we should check whether the fifo is
valid in sbi_fifo_is_empty and sbi_fifo_is_full. To this end, this patch
changes the retval from bool to int, and the two functions will return
SBI_EINVAL in the case the fifo is invalid.
Signed-off-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Linux kernel expects tlb flush SBI call to be completely synchronous i.e.
the SBI call should only return once corresponding *fence* instruction is
executed.
OpenSBI manages the outstanding TLB flush requests by keeping them in a
per hart based fifo. However, there are few corner cases that may lead to
race conditions while updating the fifo.
Currently, the caller hart waits for IPI acknowledgement via clint
address which is not a very good method as synchronization on MMIO may not
be supported in every platform. Moreover, the waiter doesn't have any way of
identifying if the IPI is received for specific tlb flush request or any
other IPI. This may lead to unpredictable behavior in supervisor/user space.
Fix this by waiting on individual fifo entries rather than MMIO address.
Currently, a relaxed loop is being used because wfi again involves MMIO write
which would be slower compared to relaxed loop. To avoid deadlock, fifo
is processed every time a hart loops for fifo enqueue or fifo sync to consume
the tlb flush requests sent by other harts.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Noisy commit, no functional changes.
Generated with an current upstream clang-format and:
clang-format -i $(find . -name \*.[ch])
Signed-off-by: Olof Johansson <olof@lixom.net>
Implement a lock enabled iteration for fifo so that
caller can determine if next entry can be skipped or
any existing entries in fifo can be updated before enqueue.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
This patch reduces memory consumed by struct sbi_fifo by droping
redundant "head" member and using u16 in-place of "unsigned long".
Signed-off-by: Anup Patel <anup.patel@wdc.com>
This patch does following improvements to sbi_fifo:
1. Use valid SBI_Exxxx error codes instead of -1
2. The sbi_fifo_is_full() and sbi_fifo_is_empty() did
not acquire qlock before accessing head and tail
hence fixed it
3. Added avail member for ease in debugging and simplifying
head/tail updates.
Due to above changes size of sbi_fifo changes from 48 bytes
to 56 bytes.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
