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FSP/CONSOLE: Close SOL session during R/R
Presently we are not closing SOL and FW console sessions during R/R. Host will continue to write to SOL buffer during FSP R/R. If there is heavy console write operation happening during FSP R/R (like running `top` command inside console), then at some point console buffer becomes full. fsp_console_write_buffer_space() returns 0 (or less than required space to write data) to host. While one thread is busy writing to console, if some other threads tries to write data to console we may see RCU stalls (like below) in kernel. kernel call trace: ------------------ [ 2082.828363] INFO: rcu_sched detected stalls on CPUs/tasks: { 32} (detected by 16, t=6002 jiffies, g=23154, c=23153, q=254769) [ 2082.828365] Task dump for CPU 32: [ 2082.828368] kworker/32:3 R running task 0 4637 2 0x00000884 [ 2082.828375] Workqueue: events dump_work_fn [ 2082.828376] Call Trace: [ 2082.828382] [c000000f1633fa00] [c00000000013b6b0] console_unlock+0x570/0x600 (unreliable) [ 2082.828384] [c000000f1633fae0] [c00000000013ba34] vprintk_emit+0x2f4/0x5c0 [ 2082.828389] [c000000f1633fb60] [c00000000099e644] printk+0x84/0x98 [ 2082.828391] [c000000f1633fb90] [c0000000000851a8] dump_work_fn+0x238/0x250 [ 2082.828394] [c000000f1633fc60] [c0000000000ecb98] process_one_work+0x198/0x4b0 [ 2082.828396] [c000000f1633fcf0] [c0000000000ed3dc] worker_thread+0x18c/0x5a0 [ 2082.828399] [c000000f1633fd80] [c0000000000f4650] kthread+0x110/0x130 [ 2082.828403] [c000000f1633fe30] [c000000000009674] ret_from_kernel_thread+0x5c/0x68 Hence lets close SOL (and FW console) during FSP R/R. CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com> Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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