diff options
| author | Anup Patel <anup.patel@wdc.com> | 2019-09-26 09:55:25 +0530 |
|---|---|---|
| committer | Anup Patel <anup@brainfault.org> | 2019-10-02 17:03:58 +0530 |
| commit | e561c6303639ed510183da25d3d54555a53371c9 (patch) | |
| tree | fa270edee3f3d2a8204d8c504d3b2ee6445a80f6 | |
| parent | 2c7bab76a2eb2366026e0482b18679fe94c1dac6 (diff) | |
lib: Fix coldboot race condition observed on emulators/simulators
If we are running on RISC-V emulator/simulator with large number of
HARTs where each HART is a regular thread under UNIX host then it is
possible that some of the secondary HARTs don't get chance to run and
sbi_hart_wake_coldboot_harts() is called before secondary HARTs call
sbi_hart_wait_for_coldboot(). In this situation, some of the secondary
HARTs will never come-out of coldboot wait loop.
To tackle this, we introduce a global flag coldboot_done which will
be protected by coldboot lock and it will be set by primary HART from
sbi_hart_wake_coldboot_harts() before waking-up secondary HARTs. We
also re-arrange acquire/release of coldboot lock to reduce further
chances of race-condition.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Nylon Chen<nylon7@andestech.com>
| -rw-r--r-- | lib/sbi/sbi_hart.c | 44 |
1 files changed, 29 insertions, 15 deletions
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index b0c087a..dee2e21 100644 --- a/lib/sbi/sbi_hart.c +++ b/lib/sbi/sbi_hart.c @@ -344,12 +344,12 @@ struct sbi_scratch *sbi_hart_id_to_scratch(struct sbi_scratch *scratch, } #define COLDBOOT_WAIT_BITMAP_SIZE __riscv_xlen -static spinlock_t coldboot_wait_bitmap_lock = SPIN_LOCK_INITIALIZER; -static unsigned long coldboot_wait_bitmap = 0; +static spinlock_t coldboot_lock = SPIN_LOCK_INITIALIZER; +static unsigned long coldboot_done = 0; +static unsigned long coldboot_wait_bitmap = 0; void sbi_hart_wait_for_coldboot(struct sbi_scratch *scratch, u32 hartid) { - unsigned long mipval; const struct sbi_platform *plat = sbi_platform_ptr(scratch); if ((sbi_platform_hart_count(plat) <= hartid) || @@ -359,19 +359,26 @@ void sbi_hart_wait_for_coldboot(struct sbi_scratch *scratch, u32 hartid) /* Set MSIE bit to receive IPI */ csr_set(CSR_MIE, MIP_MSIP); - do { - spin_lock(&coldboot_wait_bitmap_lock); - coldboot_wait_bitmap |= (1UL << hartid); - spin_unlock(&coldboot_wait_bitmap_lock); + /* Acquire coldboot lock */ + spin_lock(&coldboot_lock); + /* Mark current HART as waiting */ + coldboot_wait_bitmap |= (1UL << hartid); + + /* Wait for coldboot to finish using WFI */ + while (!coldboot_done) { + spin_unlock(&coldboot_lock); wfi(); - mipval = csr_read(CSR_MIP); + spin_lock(&coldboot_lock); + }; + + /* Unmark current HART as waiting */ + coldboot_wait_bitmap &= ~(1UL << hartid); - spin_lock(&coldboot_wait_bitmap_lock); - coldboot_wait_bitmap &= ~(1UL << hartid); - spin_unlock(&coldboot_wait_bitmap_lock); - } while (!(mipval & MIP_MSIP)); + /* Release coldboot lock */ + spin_unlock(&coldboot_lock); + /* Clear current HART IPI */ sbi_platform_ipi_clear(plat, hartid); } @@ -380,11 +387,18 @@ void sbi_hart_wake_coldboot_harts(struct sbi_scratch *scratch, u32 hartid) const struct sbi_platform *plat = sbi_platform_ptr(scratch); int max_hart = sbi_platform_hart_count(plat); + /* Acquire coldboot lock */ + spin_lock(&coldboot_lock); + + /* Mark coldboot done */ + coldboot_done = 1; + + /* Send an IPI to all HARTs waiting for coldboot */ for (int i = 0; i < max_hart; i++) { - /* send an IPI to every other hart */ - spin_lock(&coldboot_wait_bitmap_lock); if ((i != hartid) && (coldboot_wait_bitmap & (1UL << i))) sbi_platform_ipi_send(plat, i); - spin_unlock(&coldboot_wait_bitmap_lock); } + + /* Release coldboot lock */ + spin_unlock(&coldboot_lock); } |